Co-reporter:Dr. Jin-Chang Guo;Lin-Yan Feng;Ying-Jin Wang;Said Jalife;Alejro Vásquez-Espinal;José Luis Cabellos;Sudip Pan; Dr. Gabriel Merino; Dr. Hua-Jin Zhai
Angewandte Chemie International Edition 2017 Volume 56(Issue 34) pp:10174-10177
Publication Date(Web):2017/08/14
DOI:10.1002/anie.201703979
AbstractTwo low-lying structures are unveiled for the Be6B11− nanocluster system that are virtually isoenergetic. The first, triple-layered cluster has a peripheral B11 ring as central layer, being sandwiched by two Be3 rings in a coaxial fashion, albeit with no discernible interlayer Be−Be bonding. The B11 ring revolves like a flexible chain even at room temperature, gliding freely around the Be6 prism. At elevated temperatures (1000 K), the Be6 core itself also rotates; that is, two Be3 rings undergo relative rotation or twisting with respect to each other. Bonding analyses suggest four-fold (π and σ) aromaticity, offering a dilute and fluxional electron cloud that lubricates the dynamics. The second, helix-type cluster contains a B11 helical skeleton encompassing a distorted Be6 prism. It is chiral and is the first nanosystem with a boron helix. Molecular dynamics also shows that at high temperature the helix cluster readily converts into the triple-layered one.
Co-reporter:Dr. Jin-Chang Guo;Lin-Yan Feng;Ying-Jin Wang;Said Jalife;Alejro Vásquez-Espinal;José Luis Cabellos;Sudip Pan; Dr. Gabriel Merino; Dr. Hua-Jin Zhai
Angewandte Chemie 2017 Volume 129(Issue 34) pp:10308-10311
Publication Date(Web):2017/08/14
DOI:10.1002/ange.201703979
AbstractTwo low-lying structures are unveiled for the Be6B11− nanocluster system that are virtually isoenergetic. The first, triple-layered cluster has a peripheral B11 ring as central layer, being sandwiched by two Be3 rings in a coaxial fashion, albeit with no discernible interlayer Be−Be bonding. The B11 ring revolves like a flexible chain even at room temperature, gliding freely around the Be6 prism. At elevated temperatures (1000 K), the Be6 core itself also rotates; that is, two Be3 rings undergo relative rotation or twisting with respect to each other. Bonding analyses suggest four-fold (π and σ) aromaticity, offering a dilute and fluxional electron cloud that lubricates the dynamics. The second, helix-type cluster contains a B11 helical skeleton encompassing a distorted Be6 prism. It is chiral and is the first nanosystem with a boron helix. Molecular dynamics also shows that at high temperature the helix cluster readily converts into the triple-layered one.
Co-reporter:Haihan Zhou
Journal of Materials Science: Materials in Electronics 2017 Volume 28( Issue 18) pp:13983-13989
Publication Date(Web):01 June 2017
DOI:10.1007/s10854-017-7248-0
We report here a simple and effective strategy to promote supercapacitive properties of the MnO2 electrode, in which sodium dodecyl benzene sulfonate (DBS) as an anionic surfactant is added into the solution used for electrosynthesis. Morphology characterizations indicate that the DBS acts like a pore-forming agent, allowing the deposited MnO2 nanofibers to form a three-dimensional porous nano-network. The formation mechanism of porous nano-network under DBS assisted electrosynthesis is analyzed accordingly. Electrochemical measurements show that the supercapacitive performance of MnO2 electrode is effectively enhanced. The MnO2 electrode prepared with DBS presents a high specific capacitance of 259.7 F g−1 at 1 A g−1, which is increased by 30.9% with respect to 198.3 F g−1 for the electrode prepared without DBS. Notably, the cycle stability of MnO2 electrode is significantly improved due to the addition of DBS, which retains 91.0% of its initial capacitance for 2500 cycles. In contrast, the MnO2 electrode prepared without DBS only maintains 48.7%. The improved properties should promote the applications of MnO2 in electrochemical capacitors.
Co-reporter:Xue-Mei Luo, Tian Jian, Long-Jiu Cheng, Wan-Lu Li, Qiang Chen, Rui Li, Hua-Jin Zhai, Si-Dian Li, Alexander I. Boldyrev, Jun Li, Lai-Sheng Wang
Chemical Physics Letters 2017 Volume 683(Volume 683) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.cplett.2016.12.051
•Bn− monoanions have been systematically investigated up to n = 30. However, B26− has remained elusive in this size range.•Here we present a joint photoelectron spectroscopy and first-principles study on the structures and bonding of this seemingly enigmatic cluster.•Extensive global minimum searches and high-level calculations reveal that isomer I dominates the experimental spectrum and represents the smallest 2D boron cluster with a hexagonal vacancy.•Isomer III is found to contribute to the measured PE spectrum as a minor species.•Chemical bonding analyses show that isomer I can be viewed as an all-boron analog of the polycyclic aromatic hydrocarbon C17H11+.Anionic boron clusters have been systematically investigated both experimentally and theoretically up to 30 atoms and have all been proved to be planar or quasi-planar (2D) in their global minima. However, the B26− cluster has remained elusive in this size range up to now, because of its complicated potential landscape. Here we present a joint photoelectron spectroscopy (PES) and first-principles study on the structures and bonding of this seemingly enigmatic cluster. Extensive global minimum searches, followed by high-level calculations and Gibbs free energy corrections, reveal that at least three 2D isomers, I (C1, 2A), II (C1, 2A), and III (C1, 2A), could contribute to the observed PE spectrum for the B26− cluster. Isomer I, which has the lowest free energy at finite temperatures, is found to dominate the experimental spectrum and represents the smallest 2D boron cluster with a hexagonal vacancy. Distinct spectral features are observed for isomer III, which has a pentagonal hole and is found to contribute to the measured PE spectrum as a minor species. Isomer II with a close-packed triangular 2D structure, which is the global minimum at 0 K, may also contribute to the observed spectrum as a minor species. Chemical bonding analyses show that the principal isomer I can be viewed as an all-boron analog of the polycyclic aromatic hydrocarbon C17H11+ in terms of the π bonds.Download high-res image (134KB)Download full-size image
Co-reporter:Da-Zhi Li;Lin-Yan Feng;Ling Pei;Li-Juan Zhang;Shu-Guo Wu
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 3) pp:2479-2486
Publication Date(Web):2017/01/18
DOI:10.1039/C6CP07954G
Boron-based heteroatomic rings can have exotic chemical bonding, in which the p lone-pairs of heteroatoms manage to participate in delocalized π bonding, compensating for boron's electron-deficiency. We explore herein the bonding properties of ternary B–N–H systems with a pentagonal ring, using the B3N2H50/−/2− clusters as examples. Computational structural searches lead to perfectly planar C2v B3N2H5 (1, 1A1) and C2v B3N2H5− (2, 2B1) as global minima for the neutral species and monoanion, which feature a pentagonal B3N2 ring. The corresponding dianion C2v B3N2H52− (3, 1A1) is a local minimum, whose global minimum adopts a chain-like open structure. Bonding analyses reveal a five-center four-electron (5c–4e) π system in 1, dubbed the 5c–4e o-bond. It is a 4π system in the bonding/nonbonding combination, originating from two N 2p lone-pairs, which can be considered as an extension of the concept of 3c–4e ω-bond. The extra electrons in 2 and 3 occupy a markedly destabilized π orbital. Thus, a 4π configuration, rather than a π sextet according to the (4n + 2) Hückel rule, is electronically robust for the B3N2H50/−/2− system. Infrared and photoelectron spectra are predicted for 1 and 2, respectively. Structural evolution of ring-like and chain-like isomers with charge-state in B3N2H50/−/2− is elucidated. B3N2H5− (2) is used as ligand for sandwich-type complexes: C2h [(B3N2H5)2Fe]2− and C2h [(B3N2H5)2Fe]Li2.
Co-reporter:Hui Bai;Bing Bai;Lin Zhang;Wei Huang;Si-Dian Li
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 47) pp:31655-31665
Publication Date(Web):2017/12/06
DOI:10.1039/C7CP05658C
We present an extensive density-functional and wave function theory study of partially fluorinated B12Fn0/− (n = 1–6) series, which show that the global minima of B12Fn0/− (n = 2–6) are characterized to encompass a central boron double chain (BDC) nanoribbon and form stable BF2 groups at the corresponding BDC corner when n ≥ 3, but the B12F0/− system maintains the structural feature of the well-known quasi-planar C3v B12. When we put the spotlight on B12F60/− species, our single-point CCSD(T) results unveil that albeit with the 3D icosahedral isomers not being their global minima, C2 B12F6 (6.1, 1A) and C1 B12F6− (12.1, 2A) as typical low-lying isomers are 0.60 and 1.95 eV more stable than their 2D planar counterparts D3h B12F6 (6.7, 1A′) and C2v B12F6− (12.7, 2A2), respectively, alike to B12H60/− species in our previous work. Detailed bonding analyses suggest that B12Fn0/− (n = 2–5) possess ribbon aromaticity with σ plus π double conjugation along the BDC nanoribbon on account of their total number of σ and π delocalized electrons conforming the common electron configuration (π2(n+1)σ2n). Furthermore, the simulated PES spectra of the global minima of B12Fn− (n = 1–6) monoanions may facilitate their experimental characterization in the foreseeable future. Our work provides new examples for ribbon aromaticity and powerful support for the F/H/Au/BO analogy.
Co-reporter:Yonggang Yang;Dongming Jia;Ying-Jin Wang;Yuan Man;Si-Dian Li
Nanoscale (2009-Present) 2017 vol. 9(Issue 4) pp:1443-1448
Publication Date(Web):2017/01/26
DOI:10.1039/C6NR09074E
Planar boron clusters B11−, B13+, B15+, and B19− have been introduced recently as molecular Wankel motors or tank treads. Here we present a universal mechanism for these dynamically fluxional clusters; that is, they are molecular rotors with inner wheels that rotate almost freely in pseudo-rotating outer bearings, analogous to rotating molecules trapped in pseudo-rotating cages. This mechanism has significant quantum mechanical consequences: the global-minimum structures of the clusters have C2v symmetry, whereas the wheels rotating in pseudo-rotating bearings generate rosette-type shapes with D9h, D10h, D11h, and D13h symmetries. The related rotational/pseudo-rotational energies appear with characteristic band structures, effecting the dynamics.
Co-reporter:Qiang Chen;Wen-Juan Tian;Lin-Yan Feng;Hai-Gang Lu;Yue-Wen Mu;Si-Dian Li;Lai-Sheng Wang
Nanoscale (2009-Present) 2017 vol. 9(Issue 13) pp:4550-4557
Publication Date(Web):2017/03/30
DOI:10.1039/C7NR00641A
Boron clusters have been found to exhibit a variety of interesting electronic, structural, and bonding properties. Of particular interest are the recent discoveries of the 2D hexagonal B36−/0 which led to the concept of borophenes and the 3D fullerene-like B40−/0 which marked the onset of borospherene chemistry. Here, we present a joint photoelectron spectroscopic and first-principles study of B37− and B38−, which are in the transition size range between the 2D borophene-type clusters and the 3D borospherenes. These two clusters are found to possess highly stable 2D global-minimum structures consisting of a double-hexagonal vacancy. Detailed bonding analyses reveal that both B37− and B38− are all-boron analogues of coronene (C24H12) with a unique delocalized π system, featuring dual π aromaticity. These clusters with double hexagonal vacancies can be viewed as molecular motifs for the χ3-borophene which is the most stable form of borophenes recently synthesized on an Ag(111) substrate.
Co-reporter:Ying-Jin Wang;Jin-Chang Guo
Nanoscale (2009-Present) 2017 vol. 9(Issue 27) pp:9310-9316
Publication Date(Web):2017/07/13
DOI:10.1039/C7NR03193A
Planar boron clusters form dynamic rotors, either as molecular Wankel motors or subnanoscale tank treads, the latter being exemplified by an elongated B11− cluster. For an in-depth mechanistic understanding of the rotors, we investigate herein a doped boron cluster, B10C, in which a C atom isovalently substitutes B− in the B11− tank tread. Two critical structures are achieved: the Cs (1A′) global minimum (GM) with C positioned in the peripheral ring and the C2v (1A1) local minimum (LM) with C in the diatomic core. In the GM the C atom completely halts the rotation of B10C, whereas in the LM the dynamic fluxionality remains. The energy barriers for in-plane rotation differ markedly: 12.93/18.31 kcal mol−1 for GM versus 1.84 kcal mol−1 for LM at the single-point CCSD(T) level. The GM rotates via two transition states (TS), compared to one for the LM. Chemical bonding in the structures is elucidated via canonical molecular orbital (CMO) analysis, adaptive natural density partitioning (AdNDP), electron localization functions (ELFs), and Wiberg bond indices (WBI). Electron delocalization is shown to be essential for structural fluxionality. In particular, the variation of WBI from the GM or LM geometries to their TS structures correlates positively with the energy barrier, which offers a quasi-quantitative measure of the barrier height and hence controls the dynamics. This finding may be extended to all molecular rotors. It also helps rationalize why a strongly covalently bound system can behave dynamically in a manner similar to a weakly bound one; it is the latter that is generally anticipated to be structurally fluxional.
Co-reporter:Lin-Yan Feng
Physical Chemistry Chemical Physics 2017 vol. 19(Issue 35) pp:24284-24293
Publication Date(Web):2017/09/13
DOI:10.1039/C7CP04327A
We report a quantum chemical study on the structural and bonding properties of a series of boron–carbon mixed clusters with seven atoms: CnB7−n (n = 0–7). Global-minimum structures were searched using the Coalescence Kick (CK) method, followed by B3LYP/6-311+G(d) calculations for full optimizations and energetics. Top candidate structures were further benchmarked at the single-point CCSD(T) level. Structural transitions were revealed to occur successively between wheel-like, elongated, circular, and linear geometries upon the increase of C contents in the clusters. Chemical bonding was elucidated via canonical molecular orbital (CMO) analyses and adaptive natural density partitioning (AdNDP). The number of delocalized electrons (σ plus π) in the clusters was shown to vary by one at a time from 5σ to 7σ, as well as from 3π to 6π, which allows aromaticity, antiaromaticity, and conflicting aromaticity to be precisely tuned according to the (4n + 2) and 4n Hückel rules. Delocalized π and σ bonds and their electron counting appear to dictate the cluster structures of the whole series. Aromaticity in the systems was independently confirmed using nucleus-independent chemical shifts (NICSs). The monocyclic B2C5 cluster was shown to possess the greatest NICS values, consistent with its 6π plus 6σ electron countings for double aromaticity. Our analyses also shed light on the reason why C in the filled-hexagonal B6C cluster occupies a peripheral site rather than the center and why C avoids hypercoordination in B–C binary clusters. A similar argument should be valid for other B–C clusters in prior reports, such as B6C2−, B7C−, and B8C.
Co-reporter:Kang Wang, Da-Zhi Li, Rui Li, Lin-Yan Feng, Ying-Jin Wang and Hua-Jin Zhai
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 33) pp:23304-23311
Publication Date(Web):01 Aug 2016
DOI:10.1039/C6CP04464F
A chemical bonding model is presented for the bowl-like C5v B30 global-minimum cluster with a central pentagonal hole. The B30 cluster is composed of three concentric boron rings: first B5, second B10, and third B15. The first and second B rings constitute an inner double-chain ribbon and support a delocalized π sextet. The second and third rings form an outer double-chain ribbon, where 14π delocalized electrons are situated. The unique π systems lead to concentric dual π aromaticity for B30, a concept established from concerted computational data on the bases of canonical molecular orbital (CMO) analysis, adaptive natural density partitioning (AdNDP), nucleus-independent chemical shifts (NICS), and natural charge calculations. A proposal is put forward that the bowl-like B30 cluster is an exact all-boron analogue of corannulene (C20H10), a fragment of C60 fullerene. The bonding nature of corannulene is revisited and fully elucidated herein. A comparison of the bonding patterns in bowl-like C5v B30 cluster and two other structural isomers (Cs and C1) unravels the mechanism as to why the defective hole prefers to be positioned at the center.
Co-reporter:Da-Zhi Li, Rui Li, Li-Juan Zhang, Ting Ou and Hua-Jin Zhai
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 31) pp:21412-21420
Publication Date(Web):24 Jun 2016
DOI:10.1039/C6CP03952A
Boron clusters can serve as inorganic analogues of hydrocarbons or polycyclic aromatic hydrocarbons (PAHs). We present herein, based upon global searches and electronic structural calculations at the B3LYP and CCSD(T) levels, the global-minimum structures of two boron–sulfur hydride clusters: C2v B3S2H3− (1, 2B1) and C2v B3S2H3 (2, 1A1). Both species are perfectly planar and feature a five-membered B3S2 ring as the structural core, with three H atoms attached terminally to the B sites. Chemical bonding analysis shows that C2v B3S2H3− (1) has a delocalized 5π system within a heteroatomic B3S2 ring, analogous to the π bonding in cyclopentadiene, D5h C5H5. The corresponding closed-shell C2v B3S2H32− (3, 1A1) dianion is only a local minimum. At the single-point CCSD(T) level, it is 5.7 kcal mol−1 above the chain-like C1 (1A) open structure. This situation is in contrast to the cyclopentadienyl anion, C5H5−, a prototypical aromatic hydrocarbon with a π sextet. The C2v B3S2H3 (2) neutral cluster is readily obtained upon removal of one π electron from C2v B3S2H3− (1). The anion photoelectron spectrum of C2v B3S2H3− (1) and the infrared absorption spectrum of C2v B3S2H3 (2) are predicted. The C2v B3S2H3− (1) species can be stabilized in sandwich-type C2h [(B3S2H3)2Fe]2− and salt C2h [(B3S2H3)2Fe]Li2 complexes. An intriguing difference is observed between the pattern of π sextet in C2v B3S2H32− (3) dianion and that in cyclopentadienyl anion. The present work also sheds light on the mechanism of structural evolution in the B3S2H30/−/2− series with charge states.
Co-reporter:Ying-Jin Wang, Xue-Rui You, Qiang Chen, Lin-Yan Feng, Kang Wang, Ting Ou, Xiao-Yun Zhao, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 23) pp:15774-15782
Publication Date(Web):16 May 2016
DOI:10.1039/C6CP02544G
A planar, elongated B15+ cationic cluster is shown to be structurally fluxional and functions as a nanoscale tank tread on the basis of electronic structure calculations, bonding analyses, and molecular dynamics simulations. The outer B11 peripheral ring behaves like a flexible chain gliding around an inner B4 rhombus core, almost freely at the temperature of 500 K. The rotational energy barrier is only 1.37 kcal mol−1 (0.06 eV) at the PBE0/6-311+G* level, further refined to 1.66 kcal mol−1 (0.07 eV) at the single-point CCSD(T)/6-311G*//CCSD/6-311G* level. Two soft vibrational modes of 166.3 and 258.3 cm−1 are associated with the rotation, serving as double engines for the system. Bonding analysis suggests that the “island” electron clouds, both σ and π, between the peripheral ring and inner core flow and shift continuously during the intramolecular rotation, facilitating the dynamic fluxionality of the system with a small rotational barrier. The B15+ cluster, roughly 0.6 nm in dimension, is the first double-axle nanoscale tank tread equipped with two engines, which expands the concepts of molecular wheels, Wankel motors, and molecular tanks.
Co-reporter:Qiang Chen, Hai-Ru Li, Wen-Juan Tian, Hai-Gang Lu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 21) pp:14186-14190
Publication Date(Web):05 May 2016
DOI:10.1039/C6CP02369J
Based on extensive first-principles theory calculations, we present the possibility of an endohedral charge-transfer complex, Cs Ca@B37− (I), which contains a 3D aromatic fullerene-like Cs B373− (II) trianion composed of interwoven boron double chains with twelve delocalized multicenter π bonds (12 mc–2e π, m = 5, 6) over a σ skeleton, completing the Bnq borospherene family (q = n − 40) in the size range of n = 36–42.
Co-reporter:Xue-Rui You, Wen-Juan Tian, Da-Zhi Li, Ying-Jin Wang, Rui Li, Lin-Yan Feng and Hua-Jin Zhai
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 19) pp:13423-13431
Publication Date(Web):14 Apr 2016
DOI:10.1039/C6CP00101G
In a recent communication, an all-metal aromatic sandwich [Sb3Au3Sb3]3− was synthesized and characterized. We report herein a density-functional theory (DFT) study on the chemical bonding of this unique cluster, which makes use of a number of computational tools, including the canonical molecular orbital (CMO), adaptive natural density partitioning (AdNDP), Wiberg bond index, and orbital composition analyses. The 24-electron, triangular prismatic sandwich is intrinsically electron-deficient, being held together via six Sb–Sb, three Au–Au, and six Sb–Au links. A standard, qualitative bonding analysis suggests that all CMOs are primarily located on the three Sb3/Au3/Sb3 layers, three Au 6s based CMOs are fully occupied, and the three extra charges are equally shared by the two cyclo-Sb3 ligands. This bonding picture is referred to as the zeroth order model, in which the cluster can be formally formulated as [Sb31.5+Au33−Sb31.5+]3− or [Sb30Au33−Sb30]. However, the system is far more complex and covalent than the above picture. Seventeen CMOs out of 33 in total involve remarkable Sb → Au electron donation and Sb ← Au back-donation, which are characteristic of covalent bonding and effectively redistribute electrons from the Sb3 and Au3 layers to the interlayer edges. This effect collectively leads to three Sb–Au–Sb three-center two-electron (3c–2e) σ bonds as revealed in the AdNDP analyses, despite the fact that not a single such bond can be identified from the CMOs. Orbital composition analyses for the 17 CMOs allow a quantitative understanding of how electron donation and back-donation redistribute the charges within the system from the formal Sb30/Au33− charge states in the zeroth order model to the effective Sb31.5−/Au30 charge states, the latter being revealed from the natural bond orbital analysis.
Co-reporter:Qiang Chen, Hai-Ru Li, Chang-Qing Miao, Ying-Jin Wang, Hai-Gang Lu, Yue-Wen Mu, Guang-Ming Ren, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 17) pp:11610-11615
Publication Date(Web):21 Dec 2015
DOI:10.1039/C5CP06169E
Based on extensive global-minimum searches and first-principles electronic structure calculations, we present the viability of an endohedral metalloborospherene Cs Ca@B38 (1) which contains a Cs B382− (2) dianion composed of interwoven boron double chains with a σ + π double delocalization bonding pattern, extending the Bnq (q = n − 40) borospherene family from n = 39–42 to n = 38. Transition metal endohedral complexes Cs M@B38 (M = Sc, Y, Ti) (3, 5, 7) based on Cs B382− (2) are also predicted.
Co-reporter:Wen-Juan Tian, Qiang Chen, Hai-Ru Li, Miao Yan, Yue-Wen Mu, Hai-Gang Lu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 15) pp:9922-9926
Publication Date(Web):21 Mar 2016
DOI:10.1039/C6CP01279E
Based on extensive first-principles theory calculations, we present the possibility of construction of the Saturn-like charge-transfer complexes Li4&B36 (2), Li5&B36+ (3), and Li6&B362+ (4) all of which contain a perfect cage-like B364− (1) core composed of twelve interwoven boron double chains with a σ + π double delocalization bonding pattern, extending the Bnq borospherene family from n = 38–42 to n = 36 with the highest symmetry of Th.
Co-reporter:Kang Wang, Ying-Jin Wang, Da-Zhi Li, Ting Ou, Xiao-Yun Zhao and Hua-Jin Zhai
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 14) pp:9594-9601
Publication Date(Web):08 Mar 2016
DOI:10.1039/C6CP00532B
The structural and electronic properties and chemical bonding of binary Be2O2 and Si2O2 clusters have been studied using quantum chemical calculations at the B3LYP level. For the Be2O2 cluster, the potential energy surface is probed by unbiased structural searches and the global-minimum structure was established using the B3LYP calculations, complemented by PBE0 and single-point CCSD(T) calculations for top isomers. The perfectly planar D2h Be2O2 (1Ag) global minimum is well defined, being at least 3.64 eV lower in energy than alternative structures at the CCSD(T)//B3LYP/aug-cc-pVTZ level. Chemical bonding analyses show that D2h Be2O2 and Si2O2 clusters possess the rhombic four-center four-electron (4c–4e) π bond, that is, the o-bond, a conception derived from electron-deficient boron oxide clusters lately. Furthermore, the Be2O2 and Si2O2 clusters also exhibit rhombic 4c–4e σ bonds, both for the radial and tangential σ frameworks (σr and σt). The σt framework is classified as an o-bond only formally, due to the secondary contribution from the Be/Si s component. The three-fold (π, σr, and σt) o-bonds in Be2O2 and Si2O2 are considered to resemble the three-fold aromaticity in all-metal Al42− dianions. A 4c–4e o-bond makes use of four O 2p electrons, which would otherwise be two lone-pairs, for a delocalized and completely bonding orbital, as well as a residual nonbonding orbital. Three-fold o-bonds thus greatly stabilize the binary Be2O2 and Si2O2 clusters. We anticipate that the bonding concept should be applicable to additional molecular systems, including those with larger heterocyclic rings.
Co-reporter:Haihan Zhou, Hua-Jin Zhai
Organic Electronics 2016 Volume 37() pp:197-206
Publication Date(Web):October 2016
DOI:10.1016/j.orgel.2016.06.036
•CNT-GO/PPy ternary composites have been prepared by one-pot electropolymerization.•The supercapacitive performance of GO/PPy is remarkably improved by doping CNTs.•A light and thin highly flexible solid-state supercapacitor has been fabricated.•The supercapacitor presents a high specific capacitance and cycle stability.Flexible electrodes of ternary composites, in which highly conductive carbon nanotube films (CNFs) are coated with carbon nanotube-doped graphene oxide/polypyrrole (CNT-GO/PPy), have been fabricated via facile electrochemical synthesis. Long and short CNTs are separately doped into the composites (lCNT-GO/PPy and sCNT-GO/PPy) and their electrochemical performances are compared. Electrochemical measurements indicate that the doping of CNTs in the composites significantly improves the electrochemical behaviors of the GO/PPy electrodes. Notably, the lCNT-GO/PPy electrodes show superior electrochemical properties with respect to the sCNT-GO/PPy electrodes, which is related to the introduction of abundant CNTs in the former electrodes and their special microstructures. Two symmetric electrodes with the lCNT-GO/PPy composites coated on CNFs are assembled to fabricate a solid-state supercapacitor device, which features lightweight, ultrathinness, and high flexibility. The device achieves a high areal and volumetric specific capacitance of 70.0 mF cm−2 at 10 mV s−1 and 6.3 F cm−3 at 0.043 A cm−3, respectively. It also shows superior rate performance and cycle stability, with a capacitance retention rate of 87.7% for 10,000 cycles. The supercapacitor device fabricated is promising for the use in lightweight and flexible integrated electronics.
Co-reporter:Fu-Xing Pan; Lei-Jiao Li; Ying-Jin Wang; Jin-Chang Guo; Hua-Jin Zhai; Li Xu;Zhong-Ming Sun
Journal of the American Chemical Society 2015 Volume 137(Issue 34) pp:10954-10957
Publication Date(Web):August 14, 2015
DOI:10.1021/jacs.5b07730
A sandwich complex, as exemplified by ferrocene in the 1950s, usually refers to one metal center bound by two arene ligands. The subject has subsequently been extended to carbon-free aromatic ligands and multiple-metal-atom “monolayered” center, but not to an all-metal species. Here, we describe the synthesis of an unprecedented all-metal aromatic sandwich complex, [Sb3Au3Sb3]3–, which was isolated as K([2.2.2]crypt)+ salt and identified by single-crystal X-ray diffraction. Quantum chemical calculations indicate that intramolecular electron transfers for the three metallic layers (Sb → Au donation and Sb ← Au back-donation) markedly redistribute the valence electrons from the cyclo-Sb3 ligands and Au3 interlayer to the Au–Sb bonds, which hold the complex together via σ bonding. Each cyclo-Sb3 possesses aromaticity with delocalized three-center three-electron (3c-3e) π bonds, which are essentially equivalent to a 3c-4e ππ* triplet system, following the reversed 4n Hückel rule for aromaticity in a triplet state.
Co-reporter:Ying-Jin Wang, Xiao-Yun Zhao, Qiang Chen, Hua-Jin Zhai and Si-Dian Li
Nanoscale 2015 vol. 7(Issue 38) pp:16054-16060
Publication Date(Web):15 Sep 2015
DOI:10.1039/C5NR03732H
We present a concept that an elongated, planar boron cluster can serve as a “tank tread” at the sub-nanometer scale, a novel propulsion system for potential nanomachines. Density functional calculations at the PBE0/6-311+G* level for the global-minimum B11−C2v (1A1) and B11C2v (2B2) structures along the soft in-plane rotational mode allow the identification of their corresponding B11−C2v and B11C2v transition states, with small rotational energy barriers of 0.42 and 0.55 kcal mol−1, respectively. The energy barriers are refined to 0.35 and 0.60 kcal mol−1 at the single-point CCSD(T) level, suggesting that the clusters are structurally fluxional at room temperature. Molecular dynamics simulations show that B11− and B11 behave exactly like a tank tread, in which the peripheral B9 ring rotates almost freely around the B2 core. A full turn of rotation may be accomplished in around 2 ps. In contrast to molecular wheels or Wankel motors, the peripheral boron atoms in the tank tread behave as a flexible chain gliding around, rather than as a rigid wheel rotation. This finding is beyond imagination, which expands the concepts of molecular wheels and Wankel motors.
Co-reporter:Ting Ou, Wen-Juan Tian, Xue-Rui You, Ying-Jin Wang, Kang Wang and Hua-Jin Zhai
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 44) pp:29697-29706
Publication Date(Web):08 Oct 2015
DOI:10.1039/C5CP04519C
Boron oxide clusters offer intriguing molecular models for the electron-deficient system, in which the boronyl (BO) group plays a key role and the interplay between the localized BO triple bond and the multicenter electron delocalization dominates the chemical bonding. Here we report the structural, electronic, and bonding properties of the B4O4+ cationic cluster on the basis of unbiased Coalescence Kick global-minimum searches and first-principles electronic structural calculations at the B3LYP and single-point CCSD(T) levels. The B4O4+ cluster is shown to possess a Cs (1, 2A′) global minimum. It represents the smallest boron oxide species with a hexagonal boroxol (B3O3) ring as the core, terminated by a boronyl group. Chemical bonding analyses reveal double (π and σ) aromaticity in Cs B4O4+, which closely mimics that in the 3,5-dehydrophenyl cation C6H3+ (D3h, 1A1′), a prototypical molecule with double aromaticity. Alternative D2h (2, 2B3g) and C2v (3, 2A1) isomeric structures of B4O4+ are also analyzed, which are relevant to the global minima of B4O4 neutral and B4O4− anion, respectively. These three structural motifs vary drastically in terms of energetics upon changing the charge state, demonstrating an interesting case in which every electron counts. The calculated ionization potentials and electron affinities of the three corresponding neutral isomers are highly uneven, which underlie the conformational changes in the B4O4+/0/− series. The current work presents the smallest boron oxide species with a boroxol ring, establishes an analogy between boron oxides and the 3,5-dehydrophenyl cation, and enriches the chemistry of boron oxides and boronyls.
Co-reporter:Wei Wang, Qiang Chen, Ying-Jin Wang, Hui Bai, Ting-Ting Gao, Hai-Ru Li, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 30) pp:19929-19935
Publication Date(Web):29 Jun 2015
DOI:10.1039/C5CP00812C
Considerable recent research effort has been devoted to the development of boronyl (BO) chemistry. Here we predict three perfectly planar boron boronyl clusters: C2v B6O4 (1, 1A1), D2h B6O4− (2, 2B3u), and D2h B6O42− (3, 1Ag). These are established as the global-minimum structures on the basis of the coalescence kick and basin hopping structural searches and electronic structure calculations at the B3LYP/aug-cc-pVTZ level, with complementary CCSD/6-311+G* and single-point CCSD(T)/6-311+G*//B3LYP/aug-cc-pVTZ calculations for 2. The C2v B6O4 neutral cluster features a hexagonal B4O2 ring with two terminal BO groups. The D2h B6O4−/2− clusters have ethylene-like structures and are readily formulated as B2(BO)4−/2−, in which a B2 core with double bond character is bonded to four terminal BO groups. Chemical bonding analyses show that B6O4 (1) possesses an aromatic π bonding system with three delocalized, six-centered π bonds over the hexagonal ring, rendering it an inorganic analogue of benzene, whereas the B6O4−/2− (2 and 3) species closely resemble ethylene in terms of structures and bonding. This work provides new examples for the analogy between boron oxides and hydrocarbons.
Co-reporter:Qiang Chen, Ting Gao, Wen-Juan Tian, Hui Bai, Su-Yan Zhang, Hai-Ru Li, Chang-Qing Miao, Yue-Wen Mu, Hai-Gang Lu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 30) pp:19690-19694
Publication Date(Web):06 Jul 2015
DOI:10.1039/C5CP03178H
Using the newly discovered borospherenes C3 B39− and C2 B39− as molecular devices and based on extensive global-minimum searches and first-principles calculations, we present herein the possibility of the first axially chiral metalloborospherenes C3 Ca@B39+ (1, 1A) and C2 Ca@B39+ (2, 1A), which are the global minimum and the second lowest-lying isomer of CaB39+, respectively. These metalloborospherene species turn out to be charge-transfer complexes Ca2+@B39− in nature, with the Ca centre on the C3 or C2 molecular axis donating one electron to the B39 cage which behaves like a superhalogen. Molecular orbital analyses indicate that C3/C2 Ca2+@B39− possess the universal bonding pattern of σ plus π double delocalization, similar to their C3/C2 B39− parents. Molecular dynamics simulations show that both C3 Ca@B39+ (1) and C2 Ca@B39+ (2) are dynamically stable at 200 K, with the former starting to fluctuate structurally at 300 K and the latter at 400 K, again similar to C3/C2 B39−. The infrared and Raman spectra of C3/C2 Ca@B39+ (1/2) are simulated and compared with those of C3/C2 B39− to facilitate their forthcoming experimental characterization.
Co-reporter:Da-Zhi Li, Li-Juan Zhang, Ting Ou, Hai-Xia Zhang, Ling Pei, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 26) pp:16798-16804
Publication Date(Web):20 May 2015
DOI:10.1039/C5CP02394G
Based upon global searches and electronic structure calculations at the B3LYP and CCSD(T) levels, we present the global-minimum structures of two ternary B–O–H and B–S–H rhombic clusters: D2h B2O2H2 (1, 1Ag) and C2v B2S2H2 (2, 1A1). Both species feature a B2X2 (X = O or S) four-membered ring as the core, with two H atoms attached terminally. The former cluster is perfectly planar, whereas the latter undergoes a slight butterfly distortion. Bonding analyses reveal a four-center four-electron (4c–4e) o-bond in these clusters, which are 4π systems in a nonbonding/bonding combination, in contrast to an antibonding/bonding combination in a classical 4π antiaromatic hydrocarbon such as cyclobutadiene (C4H4). Clusters 1 and 2 are considered to be aromatic. The present results also help elucidate the bonding nature in the relevant heteroatomic ring B2N2H4 system and suggest that it is not appropriate to consider B2N2H4 as an inorganic cyclobutadiene, a conception that has been in existence in the literature for over 40 years. The electronic properties of the global-minimum clusters 1 and 2 are predicted. It is shown that B2O2H2 (1) and B2S2H2 (2) may serve as effective inorganic ligands to form sandwich-type transition metal complexes, such as D2d [B2O2H2]2Ni (3) and D2d [B2S2H2]2Ni (4).
Co-reporter:Hui Bai;Qiang Chen;Dr. Hua-Jin Zhai;Dr. Si-Dian Li
Angewandte Chemie 2015 Volume 127( Issue 3) pp:955-959
Publication Date(Web):
DOI:10.1002/ange.201408738
Abstract
The recent discovery of the all-boron fullerenes or borospherenes, D2d B40−/0, paves the way for borospherene chemistry. Here we report a density functional theory study on the viability of metalloborospherenes: endohedral M@B40 (M=Ca, Sr) and exohedral M&B40 (M=Be, Mg). Extensive global structural searches indicate that Ca@B40 (1, C2v, 1A1) and Sr@B40 (3, D2d, 1A1) possess almost perfect endohedral borospherene structures with a metal atom at the center, while Be&B40 (5, Cs, 1A′) and Mg&B40 (7, Cs, 1A′) favor exohedral borospherene geometries with a η7-M atom face-capping a heptagon on the waist. Metalloborospherenes provide indirect evidence for the robustness of the borospherene structural motif. The metalloborospherenes are characterized as charge-transfer complexes (M2+B402−), where an alkaline earth metal atom donates two electrons to the B40 cage. The high stability of endohedral Ca@B40 (1) and Sr@B40 (3) is due to the match in size between the host cage and the dopant. Bonding analyses indicate that all 122 valence electrons in the systems are delocalized as σ or π bonds, being distributed evenly on the cage surface, akin to the D2d B40 borospherene.
Co-reporter:Qiang Chen, Wei-Li Li, Ya-Fan Zhao, Su-Yan Zhang, Han-Shi Hu, Hui Bai, Hai-Ru Li, Wen-Juan Tian, Hai-Gang Lu, Hua-Jin Zhai, Si-Dian Li, Jun Li, and Lai-Sheng Wang
ACS Nano 2015 Volume 9(Issue 1) pp:754
Publication Date(Web):December 17, 2014
DOI:10.1021/nn506262c
Chirality plays an important role in chemistry, biology, and materials science. The recent discovery of the B40–/0 borospherenes marks the onset of a class of boron-based nanostructures. Here we report the observation of axially chiral borospherene in the B39– nanocluster on the bases of photoelectron spectroscopy, global minimum searches, and electronic structure calculations. Extensive structural searches in combination with density functional and CCSD(T) calculations show that B39– has a C3 cage global minimum with a close-lying C2 cage isomer. Both the C3 and C2 B39– cages are chiral with degenerate enantiomers. The C3 global minimum consists of three hexagons and three heptagons around the vertical C3 axis. The C2 isomer is built on two hexagons on the top and at the bottom of the cage with four heptagons around the waist. Both the C3 and C2 axially chiral isomers of B39– are present in the experiment and contribute to the observed photoelectron spectrum. The chiral borospherenes also exhibit three-dimensional aromaticity, featuring σ and π double delocalization for all valence electrons. Molecular dynamics simulations reveal that these chiral B39– cages are structurally fluxional above room temperature, compared to the highly robust D2d B40 borospherene. The current findings add chiral members to the borospherene family and indicate the structural diversity of boron-based nanomaterials.Keywords: all-boron fullerene; axial chirality; borospherene; global minimum searches; photoelectron spectroscopy; σ and π double delocalization;
Co-reporter:Hui Bai;Qiang Chen;Dr. Hua-Jin Zhai;Dr. Si-Dian Li
Angewandte Chemie International Edition 2015 Volume 54( Issue 3) pp:941-945
Publication Date(Web):
DOI:10.1002/anie.201408738
Abstract
The recent discovery of the all-boron fullerenes or borospherenes, D2d B40−/0, paves the way for borospherene chemistry. Here we report a density functional theory study on the viability of metalloborospherenes: endohedral M@B40 (M=Ca, Sr) and exohedral M&B40 (M=Be, Mg). Extensive global structural searches indicate that Ca@B40 (1, C2v, 1A1) and Sr@B40 (3, D2d, 1A1) possess almost perfect endohedral borospherene structures with a metal atom at the center, while Be&B40 (5, Cs, 1A′) and Mg&B40 (7, Cs, 1A′) favor exohedral borospherene geometries with a η7-M atom face-capping a heptagon on the waist. Metalloborospherenes provide indirect evidence for the robustness of the borospherene structural motif. The metalloborospherenes are characterized as charge-transfer complexes (M2+B402−), where an alkaline earth metal atom donates two electrons to the B40 cage. The high stability of endohedral Ca@B40 (1) and Sr@B40 (3) is due to the match in size between the host cage and the dopant. Bonding analyses indicate that all 122 valence electrons in the systems are delocalized as σ or π bonds, being distributed evenly on the cage surface, akin to the D2d B40 borospherene.
Co-reporter:Wei-Li Li ; Qiang Chen ; Wen-Juan Tian ; Hui Bai ; Ya-Fan Zhao ; Han-Shi Hu ; Jun Li ; Hua-Jin Zhai ; Si-Dian Li ;Lai-Sheng Wang
Journal of the American Chemical Society 2014 Volume 136(Issue 35) pp:12257-12260
Publication Date(Web):August 20, 2014
DOI:10.1021/ja507235s
Elemental boron is electron-deficient and cannot form graphene-like structures. Instead, triangular boron lattices with hexagonal vacancies have been predicted to be stable. A recent experimental and computational study showed that the B36 cluster has a planar C6v structure with a central hexagonal hole, providing the first experimental evidence for the viability of atom-thin boron sheets with hexagonal vacancies, dubbed borophene. Here we report a boron cluster with a double-hexagonal vacancy as a new and more flexible structural motif for borophene. Photoelectron spectrum of B35– displays a simple pattern with certain similarity to that of B36–. Global minimum searches find that both B35– and B35 possess planar hexagonal structures, similar to that of B36, except a missing interior B atom that creates a double-hexagonal vacancy. The closed-shell B35– is found to exhibit triple π aromaticity with 11 delocalized π bonds, analogous to benzo(g,h,i)perylene (C22H12). The B35 cluster can be used to build atom-thin boron sheets with various hexagonal hole densities, providing further experimental evidence for the viability of borophene.
Co-reporter:Qiang Chen, Guang-Feng Wei, Wen-Juan Tian, Hui Bai, Zhi-Pan Liu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 34) pp:18282-18287
Publication Date(Web):16 Jul 2014
DOI:10.1039/C4CP02032D
Flat boron has recently emerged as a fascinating concept in cluster science. Here we present computational evidence for the quasi-planar all-boron aromatic B36 (C6v, 1A1) and B36− (C2v, 2A1) clusters, established as the global-minimum structures on the basis of Stochastic Surface Walking (SSW) searches. The energetics for low-lying isomeric structures are evaluated using the validated density-functional method at the PBE0/6-311+G* level. Our global-minimum structures are in line with a recent report (Z. A. Piazza et al., Nat. Commun., 2014, 5, 3113). These structures consist of two-dimensional close-packing boron with a perfect hexagonal hole at the center, which may serve as molecular models for the monolayer boron α sheet. Chemical bonding analysis indicates that B36 and B36− are all-boron analogues of coronene (C24H12), featuring concentric dual π aromaticity with an inner π sextet and an outer π sextet. The hydrogenated B36H6 (C6v, 1A1) model cluster shows similar bonding properties, which possesses concentric triple aromaticity with inner π, outer π, and outer σ sextets.
Co-reporter:Qiang Chen, Haigang Lu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 16) pp:7274-7279
Publication Date(Web):20 Feb 2014
DOI:10.1039/C4CP00406J
We explore the structural and bonding properties of the electron-deficient boron oxide clusters, using a series of B3On−/0/+ (n = 2–4) clusters as examples. Global-minimum structures of these boron oxide clusters are identified via unbiased Coalescence Kick and Basin Hopping searches, which show a remarkable size and charge-state dependence. An array of new bonding elements are revealed: core boronyl groups, dual 3c–4e hypervalent bonds (ω-bonds), and rhombic 4c–4e bonds (o-bonds). In favorable cases, oxygen can exhaust all its 2s/2p electrons to facilitate the formation of B–O bonds. The current findings should help understand the bonding nature of low-dimensional boron oxide nanomaterials and bulk boron oxides.
Co-reporter:Wen-Juan Tian, Hong-Guang Xu, Xiang-Yu Kong, Qiang Chen, Wei-Jun Zheng, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 11) pp:5129-5136
Publication Date(Web):16 Jan 2014
DOI:10.1039/C3CP55362K
We report on the structural and electronic properties and chemical bonding in a series of lithium and gold alloyed boron oxide clusters: B2O3−, LiB2O3−, AuB2O3−, and LiAuB2O3−. The clusters have been produced by laser vaporization and characterized using photoelectron spectroscopy, in combination with the Coalescence Kick and Basin Hopping global-minimum searches and density-functional theory and molecular orbital theory calculations. Electron affinities of B2O3, LiB2O3, AuB2O3, and LiAuB2O3 neutral clusters are measured to be 1.45 ± 0.08, 4.25 ± 0.08, 6.05 ± 0.08, and 2.40 ± 0.08 eV, respectively. The experimental and computational data allow the cluster structures to be established for the anions as well as their neutrals. While B2O3− (C2v) is bent, the three alloy clusters, LiB2O3− (C∞v), AuB2O3− (Cs), and LiAuB2O3− (C∞v), adopt linear or quasi-linear geometries with a metal center inserted between BO and OBO subunits, featuring charge transfer complexes, covalent gold, hyperhalogen, and dual three-center four-electron (3c-4e) π hyperbonds. The current results suggest the possibility of altering and fine-tuning the properties of boron oxides via alloying, which may lead to markedly different electronic structures and chemical reactivities. The LiB2O3 cluster belongs to the class of oxidizing agents called superhalogens, whereas AuB2O3 is a hyperhalogen species. Dual 3c-4e π hyperbonds represent a critical bonding element in boron oxides and are considered to be the root of delocalized bonding and aromaticity therein.
Co-reporter:Hui Bai, Qiang Chen, Chang-Qing Miao, Yue-Wen Mu, Yan-Bo Wu, Hai-Gang Lu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2013 vol. 15(Issue 43) pp:18872-18880
Publication Date(Web):10 Sep 2013
DOI:10.1039/C3CP53761G
We report an extensive density-functional theory and coupled-cluster CCSD(T) study on boron dihydride dianion clusters BnH22− (n = 6–22) and their dilithiated Li2BnH20/− salt complexes. Double-chain (DC) planar nanoribbon structures are confirmed as the global minima for the BnH22− (n = 6–22) clusters. Charging proves to be an effective mechanism to stabilize and extend the DC planar nanostructures, capable of producing elongated boron nanoribbons with variable lengths between 4.3–17.0 Å. For the dilithiated salts, the DC planar nanoribbons are lowest in energy up to Li2B14H2 and represent true minima for all Li2BnH20/− (n = 6–22) species. These boron nanostructures may be viewed as molecular zippers, in which two atomically-thin molecular wires are zipped together via delocalized bonds. Bonding analysis reveals the nature of π plus σ double conjugation in the lithiated DC nanoribbon Li2BnH20/− (n up to 22) model clusters, which exhibit a 4n pattern in adiabatic detachment energies, ionization potentials, and second-order differences in total energies. Band structure analysis of the infinite DC boron nanoribbon structure also reveals that both π and σ electrons participate in electric conduction, much different from the monolayer boron α-sheet in which only π electrons act as carriers. A concept of “ribbon aromaticity” is proposed for this quasi-one-dimensional system, where regular π versus σ alternation of the delocalized electron clouds along the nanoribbons results in enhanced stability for a series of “magic” nanoribbon clusters. The total number of delocalized π and σ electrons for ribbon aromaticity collectively conforms to the (4n + 2) Hückel rule. Ribbon aromaticity appears to be a general concept in other nanoribbon systems as well.
Co-reporter:Hua-Jin Zhai ; Qiang Chen ; Hui Bai ; Si-Dian Li ;Lai-Sheng Wang
Accounts of Chemical Research () pp:
Publication Date(Web):June 10, 2014
DOI:10.1021/ar500136j
The BO groups also dominate the structures and bonding of boron oxide clusters and boron boronyl complexes, in which BO groups occupy terminal, bridging, or face-capping positions. The bridging η2-BO groups feature three-center two-electron bonds, akin to the BHB τ bonds in boranes. A close isolobal analogy is thus established between boron oxide clusters and boranes, offering vast opportunities for the rational design of novel boron oxide clusters and compounds. Boron boronyl clusters may also serve as molecular models for mechanistic understanding of the combustion of boron and boranes. An effort to tune the B versus O composition in boron oxide clusters leads to the discovery of boronyl boroxine, D3h B3O3(BO)3, an analogue of boroxine and borazine and a new member of the “inorganic benzene” family. Furthermore, a unique concept of π and σ double conjugation is proposed for the first time to elucidate the structures and bonding in the double-chain nanoribbon boron diboronyl clusters, which appear to be inorganic analogues of polyenes, cumulenes, and polyynes. This Account concludes with a brief outlook for the future directions in this emerging and expanding research field.
Co-reporter:Qiang Chen, Hai-Ru Li, Wen-Juan Tian, Hai-Gang Lu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 21) pp:NaN14190-14190
Publication Date(Web):2016/05/05
DOI:10.1039/C6CP02369J
Based on extensive first-principles theory calculations, we present the possibility of an endohedral charge-transfer complex, Cs Ca@B37− (I), which contains a 3D aromatic fullerene-like Cs B373− (II) trianion composed of interwoven boron double chains with twelve delocalized multicenter π bonds (12 mc–2e π, m = 5, 6) over a σ skeleton, completing the Bnq borospherene family (q = n − 40) in the size range of n = 36–42.
Co-reporter:Ting Ou, Wen-Juan Tian, Xue-Rui You, Ying-Jin Wang, Kang Wang and Hua-Jin Zhai
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 44) pp:NaN29706-29706
Publication Date(Web):2015/10/08
DOI:10.1039/C5CP04519C
Boron oxide clusters offer intriguing molecular models for the electron-deficient system, in which the boronyl (BO) group plays a key role and the interplay between the localized BO triple bond and the multicenter electron delocalization dominates the chemical bonding. Here we report the structural, electronic, and bonding properties of the B4O4+ cationic cluster on the basis of unbiased Coalescence Kick global-minimum searches and first-principles electronic structural calculations at the B3LYP and single-point CCSD(T) levels. The B4O4+ cluster is shown to possess a Cs (1, 2A′) global minimum. It represents the smallest boron oxide species with a hexagonal boroxol (B3O3) ring as the core, terminated by a boronyl group. Chemical bonding analyses reveal double (π and σ) aromaticity in Cs B4O4+, which closely mimics that in the 3,5-dehydrophenyl cation C6H3+ (D3h, 1A1′), a prototypical molecule with double aromaticity. Alternative D2h (2, 2B3g) and C2v (3, 2A1) isomeric structures of B4O4+ are also analyzed, which are relevant to the global minima of B4O4 neutral and B4O4− anion, respectively. These three structural motifs vary drastically in terms of energetics upon changing the charge state, demonstrating an interesting case in which every electron counts. The calculated ionization potentials and electron affinities of the three corresponding neutral isomers are highly uneven, which underlie the conformational changes in the B4O4+/0/− series. The current work presents the smallest boron oxide species with a boroxol ring, establishes an analogy between boron oxides and the 3,5-dehydrophenyl cation, and enriches the chemistry of boron oxides and boronyls.
Co-reporter:Wei Wang, Qiang Chen, Ying-Jin Wang, Hui Bai, Ting-Ting Gao, Hai-Ru Li, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 30) pp:NaN19935-19935
Publication Date(Web):2015/06/29
DOI:10.1039/C5CP00812C
Considerable recent research effort has been devoted to the development of boronyl (BO) chemistry. Here we predict three perfectly planar boron boronyl clusters: C2v B6O4 (1, 1A1), D2h B6O4− (2, 2B3u), and D2h B6O42− (3, 1Ag). These are established as the global-minimum structures on the basis of the coalescence kick and basin hopping structural searches and electronic structure calculations at the B3LYP/aug-cc-pVTZ level, with complementary CCSD/6-311+G* and single-point CCSD(T)/6-311+G*//B3LYP/aug-cc-pVTZ calculations for 2. The C2v B6O4 neutral cluster features a hexagonal B4O2 ring with two terminal BO groups. The D2h B6O4−/2− clusters have ethylene-like structures and are readily formulated as B2(BO)4−/2−, in which a B2 core with double bond character is bonded to four terminal BO groups. Chemical bonding analyses show that B6O4 (1) possesses an aromatic π bonding system with three delocalized, six-centered π bonds over the hexagonal ring, rendering it an inorganic analogue of benzene, whereas the B6O4−/2− (2 and 3) species closely resemble ethylene in terms of structures and bonding. This work provides new examples for the analogy between boron oxides and hydrocarbons.
Co-reporter:Wen-Juan Tian, Hong-Guang Xu, Xiang-Yu Kong, Qiang Chen, Wei-Jun Zheng, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 11) pp:NaN5136-5136
Publication Date(Web):2014/01/16
DOI:10.1039/C3CP55362K
We report on the structural and electronic properties and chemical bonding in a series of lithium and gold alloyed boron oxide clusters: B2O3−, LiB2O3−, AuB2O3−, and LiAuB2O3−. The clusters have been produced by laser vaporization and characterized using photoelectron spectroscopy, in combination with the Coalescence Kick and Basin Hopping global-minimum searches and density-functional theory and molecular orbital theory calculations. Electron affinities of B2O3, LiB2O3, AuB2O3, and LiAuB2O3 neutral clusters are measured to be 1.45 ± 0.08, 4.25 ± 0.08, 6.05 ± 0.08, and 2.40 ± 0.08 eV, respectively. The experimental and computational data allow the cluster structures to be established for the anions as well as their neutrals. While B2O3− (C2v) is bent, the three alloy clusters, LiB2O3− (C∞v), AuB2O3− (Cs), and LiAuB2O3− (C∞v), adopt linear or quasi-linear geometries with a metal center inserted between BO and OBO subunits, featuring charge transfer complexes, covalent gold, hyperhalogen, and dual three-center four-electron (3c-4e) π hyperbonds. The current results suggest the possibility of altering and fine-tuning the properties of boron oxides via alloying, which may lead to markedly different electronic structures and chemical reactivities. The LiB2O3 cluster belongs to the class of oxidizing agents called superhalogens, whereas AuB2O3 is a hyperhalogen species. Dual 3c-4e π hyperbonds represent a critical bonding element in boron oxides and are considered to be the root of delocalized bonding and aromaticity therein.
Co-reporter:Hui Bai, Qiang Chen, Chang-Qing Miao, Yue-Wen Mu, Yan-Bo Wu, Hai-Gang Lu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2013 - vol. 15(Issue 43) pp:NaN18880-18880
Publication Date(Web):2013/09/10
DOI:10.1039/C3CP53761G
We report an extensive density-functional theory and coupled-cluster CCSD(T) study on boron dihydride dianion clusters BnH22− (n = 6–22) and their dilithiated Li2BnH20/− salt complexes. Double-chain (DC) planar nanoribbon structures are confirmed as the global minima for the BnH22− (n = 6–22) clusters. Charging proves to be an effective mechanism to stabilize and extend the DC planar nanostructures, capable of producing elongated boron nanoribbons with variable lengths between 4.3–17.0 Å. For the dilithiated salts, the DC planar nanoribbons are lowest in energy up to Li2B14H2 and represent true minima for all Li2BnH20/− (n = 6–22) species. These boron nanostructures may be viewed as molecular zippers, in which two atomically-thin molecular wires are zipped together via delocalized bonds. Bonding analysis reveals the nature of π plus σ double conjugation in the lithiated DC nanoribbon Li2BnH20/− (n up to 22) model clusters, which exhibit a 4n pattern in adiabatic detachment energies, ionization potentials, and second-order differences in total energies. Band structure analysis of the infinite DC boron nanoribbon structure also reveals that both π and σ electrons participate in electric conduction, much different from the monolayer boron α-sheet in which only π electrons act as carriers. A concept of “ribbon aromaticity” is proposed for this quasi-one-dimensional system, where regular π versus σ alternation of the delocalized electron clouds along the nanoribbons results in enhanced stability for a series of “magic” nanoribbon clusters. The total number of delocalized π and σ electrons for ribbon aromaticity collectively conforms to the (4n + 2) Hückel rule. Ribbon aromaticity appears to be a general concept in other nanoribbon systems as well.
Co-reporter:Qiang Chen, Guang-Feng Wei, Wen-Juan Tian, Hui Bai, Zhi-Pan Liu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 34) pp:NaN18287-18287
Publication Date(Web):2014/07/16
DOI:10.1039/C4CP02032D
Flat boron has recently emerged as a fascinating concept in cluster science. Here we present computational evidence for the quasi-planar all-boron aromatic B36 (C6v, 1A1) and B36− (C2v, 2A1) clusters, established as the global-minimum structures on the basis of Stochastic Surface Walking (SSW) searches. The energetics for low-lying isomeric structures are evaluated using the validated density-functional method at the PBE0/6-311+G* level. Our global-minimum structures are in line with a recent report (Z. A. Piazza et al., Nat. Commun., 2014, 5, 3113). These structures consist of two-dimensional close-packing boron with a perfect hexagonal hole at the center, which may serve as molecular models for the monolayer boron α sheet. Chemical bonding analysis indicates that B36 and B36− are all-boron analogues of coronene (C24H12), featuring concentric dual π aromaticity with an inner π sextet and an outer π sextet. The hydrogenated B36H6 (C6v, 1A1) model cluster shows similar bonding properties, which possesses concentric triple aromaticity with inner π, outer π, and outer σ sextets.
Co-reporter:Qiang Chen, Haigang Lu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 16) pp:NaN7279-7279
Publication Date(Web):2014/02/20
DOI:10.1039/C4CP00406J
We explore the structural and bonding properties of the electron-deficient boron oxide clusters, using a series of B3On−/0/+ (n = 2–4) clusters as examples. Global-minimum structures of these boron oxide clusters are identified via unbiased Coalescence Kick and Basin Hopping searches, which show a remarkable size and charge-state dependence. An array of new bonding elements are revealed: core boronyl groups, dual 3c–4e hypervalent bonds (ω-bonds), and rhombic 4c–4e bonds (o-bonds). In favorable cases, oxygen can exhaust all its 2s/2p electrons to facilitate the formation of B–O bonds. The current findings should help understand the bonding nature of low-dimensional boron oxide nanomaterials and bulk boron oxides.
Co-reporter:Qiang Chen, Ting Gao, Wen-Juan Tian, Hui Bai, Su-Yan Zhang, Hai-Ru Li, Chang-Qing Miao, Yue-Wen Mu, Hai-Gang Lu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 30) pp:NaN19694-19694
Publication Date(Web):2015/07/06
DOI:10.1039/C5CP03178H
Using the newly discovered borospherenes C3 B39− and C2 B39− as molecular devices and based on extensive global-minimum searches and first-principles calculations, we present herein the possibility of the first axially chiral metalloborospherenes C3 Ca@B39+ (1, 1A) and C2 Ca@B39+ (2, 1A), which are the global minimum and the second lowest-lying isomer of CaB39+, respectively. These metalloborospherene species turn out to be charge-transfer complexes Ca2+@B39− in nature, with the Ca centre on the C3 or C2 molecular axis donating one electron to the B39 cage which behaves like a superhalogen. Molecular orbital analyses indicate that C3/C2 Ca2+@B39− possess the universal bonding pattern of σ plus π double delocalization, similar to their C3/C2 B39− parents. Molecular dynamics simulations show that both C3 Ca@B39+ (1) and C2 Ca@B39+ (2) are dynamically stable at 200 K, with the former starting to fluctuate structurally at 300 K and the latter at 400 K, again similar to C3/C2 B39−. The infrared and Raman spectra of C3/C2 Ca@B39+ (1/2) are simulated and compared with those of C3/C2 B39− to facilitate their forthcoming experimental characterization.
Co-reporter:Da-Zhi Li, Li-Juan Zhang, Ting Ou, Hai-Xia Zhang, Ling Pei, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 26) pp:NaN16804-16804
Publication Date(Web):2015/05/20
DOI:10.1039/C5CP02394G
Based upon global searches and electronic structure calculations at the B3LYP and CCSD(T) levels, we present the global-minimum structures of two ternary B–O–H and B–S–H rhombic clusters: D2h B2O2H2 (1, 1Ag) and C2v B2S2H2 (2, 1A1). Both species feature a B2X2 (X = O or S) four-membered ring as the core, with two H atoms attached terminally. The former cluster is perfectly planar, whereas the latter undergoes a slight butterfly distortion. Bonding analyses reveal a four-center four-electron (4c–4e) o-bond in these clusters, which are 4π systems in a nonbonding/bonding combination, in contrast to an antibonding/bonding combination in a classical 4π antiaromatic hydrocarbon such as cyclobutadiene (C4H4). Clusters 1 and 2 are considered to be aromatic. The present results also help elucidate the bonding nature in the relevant heteroatomic ring B2N2H4 system and suggest that it is not appropriate to consider B2N2H4 as an inorganic cyclobutadiene, a conception that has been in existence in the literature for over 40 years. The electronic properties of the global-minimum clusters 1 and 2 are predicted. It is shown that B2O2H2 (1) and B2S2H2 (2) may serve as effective inorganic ligands to form sandwich-type transition metal complexes, such as D2d [B2O2H2]2Ni (3) and D2d [B2S2H2]2Ni (4).
Co-reporter:Da-Zhi Li, Rui Li, Li-Juan Zhang, Ting Ou and Hua-Jin Zhai
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 31) pp:NaN21420-21420
Publication Date(Web):2016/06/24
DOI:10.1039/C6CP03952A
Boron clusters can serve as inorganic analogues of hydrocarbons or polycyclic aromatic hydrocarbons (PAHs). We present herein, based upon global searches and electronic structural calculations at the B3LYP and CCSD(T) levels, the global-minimum structures of two boron–sulfur hydride clusters: C2v B3S2H3− (1, 2B1) and C2v B3S2H3 (2, 1A1). Both species are perfectly planar and feature a five-membered B3S2 ring as the structural core, with three H atoms attached terminally to the B sites. Chemical bonding analysis shows that C2v B3S2H3− (1) has a delocalized 5π system within a heteroatomic B3S2 ring, analogous to the π bonding in cyclopentadiene, D5h C5H5. The corresponding closed-shell C2v B3S2H32− (3, 1A1) dianion is only a local minimum. At the single-point CCSD(T) level, it is 5.7 kcal mol−1 above the chain-like C1 (1A) open structure. This situation is in contrast to the cyclopentadienyl anion, C5H5−, a prototypical aromatic hydrocarbon with a π sextet. The C2v B3S2H3 (2) neutral cluster is readily obtained upon removal of one π electron from C2v B3S2H3− (1). The anion photoelectron spectrum of C2v B3S2H3− (1) and the infrared absorption spectrum of C2v B3S2H3 (2) are predicted. The C2v B3S2H3− (1) species can be stabilized in sandwich-type C2h [(B3S2H3)2Fe]2− and salt C2h [(B3S2H3)2Fe]Li2 complexes. An intriguing difference is observed between the pattern of π sextet in C2v B3S2H32− (3) dianion and that in cyclopentadienyl anion. The present work also sheds light on the mechanism of structural evolution in the B3S2H30/−/2− series with charge states.
Co-reporter:Kang Wang, Da-Zhi Li, Rui Li, Lin-Yan Feng, Ying-Jin Wang and Hua-Jin Zhai
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 33) pp:NaN23311-23311
Publication Date(Web):2016/08/01
DOI:10.1039/C6CP04464F
A chemical bonding model is presented for the bowl-like C5v B30 global-minimum cluster with a central pentagonal hole. The B30 cluster is composed of three concentric boron rings: first B5, second B10, and third B15. The first and second B rings constitute an inner double-chain ribbon and support a delocalized π sextet. The second and third rings form an outer double-chain ribbon, where 14π delocalized electrons are situated. The unique π systems lead to concentric dual π aromaticity for B30, a concept established from concerted computational data on the bases of canonical molecular orbital (CMO) analysis, adaptive natural density partitioning (AdNDP), nucleus-independent chemical shifts (NICS), and natural charge calculations. A proposal is put forward that the bowl-like B30 cluster is an exact all-boron analogue of corannulene (C20H10), a fragment of C60 fullerene. The bonding nature of corannulene is revisited and fully elucidated herein. A comparison of the bonding patterns in bowl-like C5v B30 cluster and two other structural isomers (Cs and C1) unravels the mechanism as to why the defective hole prefers to be positioned at the center.
Co-reporter:Ying-Jin Wang, Xue-Rui You, Qiang Chen, Lin-Yan Feng, Kang Wang, Ting Ou, Xiao-Yun Zhao, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 23) pp:NaN15782-15782
Publication Date(Web):2016/05/16
DOI:10.1039/C6CP02544G
A planar, elongated B15+ cationic cluster is shown to be structurally fluxional and functions as a nanoscale tank tread on the basis of electronic structure calculations, bonding analyses, and molecular dynamics simulations. The outer B11 peripheral ring behaves like a flexible chain gliding around an inner B4 rhombus core, almost freely at the temperature of 500 K. The rotational energy barrier is only 1.37 kcal mol−1 (0.06 eV) at the PBE0/6-311+G* level, further refined to 1.66 kcal mol−1 (0.07 eV) at the single-point CCSD(T)/6-311G*//CCSD/6-311G* level. Two soft vibrational modes of 166.3 and 258.3 cm−1 are associated with the rotation, serving as double engines for the system. Bonding analysis suggests that the “island” electron clouds, both σ and π, between the peripheral ring and inner core flow and shift continuously during the intramolecular rotation, facilitating the dynamic fluxionality of the system with a small rotational barrier. The B15+ cluster, roughly 0.6 nm in dimension, is the first double-axle nanoscale tank tread equipped with two engines, which expands the concepts of molecular wheels, Wankel motors, and molecular tanks.
Co-reporter:Xue-Rui You, Wen-Juan Tian, Da-Zhi Li, Ying-Jin Wang, Rui Li, Lin-Yan Feng and Hua-Jin Zhai
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 19) pp:NaN13431-13431
Publication Date(Web):2016/04/14
DOI:10.1039/C6CP00101G
In a recent communication, an all-metal aromatic sandwich [Sb3Au3Sb3]3− was synthesized and characterized. We report herein a density-functional theory (DFT) study on the chemical bonding of this unique cluster, which makes use of a number of computational tools, including the canonical molecular orbital (CMO), adaptive natural density partitioning (AdNDP), Wiberg bond index, and orbital composition analyses. The 24-electron, triangular prismatic sandwich is intrinsically electron-deficient, being held together via six Sb–Sb, three Au–Au, and six Sb–Au links. A standard, qualitative bonding analysis suggests that all CMOs are primarily located on the three Sb3/Au3/Sb3 layers, three Au 6s based CMOs are fully occupied, and the three extra charges are equally shared by the two cyclo-Sb3 ligands. This bonding picture is referred to as the zeroth order model, in which the cluster can be formally formulated as [Sb31.5+Au33−Sb31.5+]3− or [Sb30Au33−Sb30]. However, the system is far more complex and covalent than the above picture. Seventeen CMOs out of 33 in total involve remarkable Sb → Au electron donation and Sb ← Au back-donation, which are characteristic of covalent bonding and effectively redistribute electrons from the Sb3 and Au3 layers to the interlayer edges. This effect collectively leads to three Sb–Au–Sb three-center two-electron (3c–2e) σ bonds as revealed in the AdNDP analyses, despite the fact that not a single such bond can be identified from the CMOs. Orbital composition analyses for the 17 CMOs allow a quantitative understanding of how electron donation and back-donation redistribute the charges within the system from the formal Sb30/Au33− charge states in the zeroth order model to the effective Sb31.5−/Au30 charge states, the latter being revealed from the natural bond orbital analysis.
Co-reporter:Qiang Chen, Hai-Ru Li, Chang-Qing Miao, Ying-Jin Wang, Hai-Gang Lu, Yue-Wen Mu, Guang-Ming Ren, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 17) pp:NaN11615-11615
Publication Date(Web):2015/12/21
DOI:10.1039/C5CP06169E
Based on extensive global-minimum searches and first-principles electronic structure calculations, we present the viability of an endohedral metalloborospherene Cs Ca@B38 (1) which contains a Cs B382− (2) dianion composed of interwoven boron double chains with a σ + π double delocalization bonding pattern, extending the Bnq (q = n − 40) borospherene family from n = 39–42 to n = 38. Transition metal endohedral complexes Cs M@B38 (M = Sc, Y, Ti) (3, 5, 7) based on Cs B382− (2) are also predicted.
Co-reporter:Wen-Juan Tian, Qiang Chen, Hai-Ru Li, Miao Yan, Yue-Wen Mu, Hai-Gang Lu, Hua-Jin Zhai and Si-Dian Li
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 15) pp:NaN9926-9926
Publication Date(Web):2016/03/21
DOI:10.1039/C6CP01279E
Based on extensive first-principles theory calculations, we present the possibility of construction of the Saturn-like charge-transfer complexes Li4&B36 (2), Li5&B36+ (3), and Li6&B362+ (4) all of which contain a perfect cage-like B364− (1) core composed of twelve interwoven boron double chains with a σ + π double delocalization bonding pattern, extending the Bnq borospherene family from n = 38–42 to n = 36 with the highest symmetry of Th.
Co-reporter:Kang Wang, Ying-Jin Wang, Da-Zhi Li, Ting Ou, Xiao-Yun Zhao and Hua-Jin Zhai
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 14) pp:NaN9601-9601
Publication Date(Web):2016/03/08
DOI:10.1039/C6CP00532B
The structural and electronic properties and chemical bonding of binary Be2O2 and Si2O2 clusters have been studied using quantum chemical calculations at the B3LYP level. For the Be2O2 cluster, the potential energy surface is probed by unbiased structural searches and the global-minimum structure was established using the B3LYP calculations, complemented by PBE0 and single-point CCSD(T) calculations for top isomers. The perfectly planar D2h Be2O2 (1Ag) global minimum is well defined, being at least 3.64 eV lower in energy than alternative structures at the CCSD(T)//B3LYP/aug-cc-pVTZ level. Chemical bonding analyses show that D2h Be2O2 and Si2O2 clusters possess the rhombic four-center four-electron (4c–4e) π bond, that is, the o-bond, a conception derived from electron-deficient boron oxide clusters lately. Furthermore, the Be2O2 and Si2O2 clusters also exhibit rhombic 4c–4e σ bonds, both for the radial and tangential σ frameworks (σr and σt). The σt framework is classified as an o-bond only formally, due to the secondary contribution from the Be/Si s component. The three-fold (π, σr, and σt) o-bonds in Be2O2 and Si2O2 are considered to resemble the three-fold aromaticity in all-metal Al42− dianions. A 4c–4e o-bond makes use of four O 2p electrons, which would otherwise be two lone-pairs, for a delocalized and completely bonding orbital, as well as a residual nonbonding orbital. Three-fold o-bonds thus greatly stabilize the binary Be2O2 and Si2O2 clusters. We anticipate that the bonding concept should be applicable to additional molecular systems, including those with larger heterocyclic rings.
Co-reporter:Da-Zhi Li, Lin-Yan Feng, Ling Pei, Li-Juan Zhang, Shu-Guo Wu and Hua-Jin Zhai
Physical Chemistry Chemical Physics 2017 - vol. 19(Issue 3) pp:NaN2486-2486
Publication Date(Web):2016/12/19
DOI:10.1039/C6CP07954G
Boron-based heteroatomic rings can have exotic chemical bonding, in which the p lone-pairs of heteroatoms manage to participate in delocalized π bonding, compensating for boron's electron-deficiency. We explore herein the bonding properties of ternary B–N–H systems with a pentagonal ring, using the B3N2H50/−/2− clusters as examples. Computational structural searches lead to perfectly planar C2v B3N2H5 (1, 1A1) and C2v B3N2H5− (2, 2B1) as global minima for the neutral species and monoanion, which feature a pentagonal B3N2 ring. The corresponding dianion C2v B3N2H52− (3, 1A1) is a local minimum, whose global minimum adopts a chain-like open structure. Bonding analyses reveal a five-center four-electron (5c–4e) π system in 1, dubbed the 5c–4e o-bond. It is a 4π system in the bonding/nonbonding combination, originating from two N 2p lone-pairs, which can be considered as an extension of the concept of 3c–4e ω-bond. The extra electrons in 2 and 3 occupy a markedly destabilized π orbital. Thus, a 4π configuration, rather than a π sextet according to the (4n + 2) Hückel rule, is electronically robust for the B3N2H50/−/2− system. Infrared and photoelectron spectra are predicted for 1 and 2, respectively. Structural evolution of ring-like and chain-like isomers with charge-state in B3N2H50/−/2− is elucidated. B3N2H5− (2) is used as ligand for sandwich-type complexes: C2h [(B3N2H5)2Fe]2− and C2h [(B3N2H5)2Fe]Li2.
![Cyclopropa[cd]pentalene, 2a,2b,4a,4b-tetrahydro-](/data/chemimg/945100/6909-37-1.png)
![Cyclopropa[cd]pentalene, 2a,2b,4a,4b-tetrahydro-](/data/chemimg/945100/6909-37-1_b.png)
![dibenzo[ghi,mno]fluoranthene](http://img.cochemist.com/ccimg/5900/5821-51-2.png)
![dibenzo[ghi,mno]fluoranthene](http://img.cochemist.com/ccimg/5900/5821-51-2_b.png)