2,6-Di(1-methyl-pyrazol-3-yl)pyridine (LMe), 2,6-di(1-allyl-pyrazol-3-yl)pyridine (LAll), 2,6-di(1-benzyl-pyrazol-3-yl)pyridine (LBz) and di(1-isopropyl-pyrazol-3-yl)pyridine (LiPr) have been synthesized by alkylation of deprotonated di{1H-pyrazol-3-yl}pyridine (3-bpp), and converted to salts of the corresponding [Fe(LR)2]2+ complexes (R = Me, All, Bz and iPr). Crystal structures of [Fe(LMe)2]X2 (X− = BF4−, ClO4− and PF6−), [Fe(LAll)2][BF4]2, [Fe(LBz)2][BF4]2 and [Fe(LiPr)2][PF6]2 have been determined at 150 K. All of these contain high-spin iron centres except [Fe(LMe)2][BF4]2·xH2O, which is predominantly low-spin at that temperature. All the complexes are high-spin between 5 and 300 K as solvent-free bulk powders, and are also high-spin in (CD3)2CO solution between 193 and 293 K. This was unexpected, since the parent complex [Fe(3-bpp)2]2+ undergoes spin-crossover in the same solvent with T½ = 247 K [40]. The high-spin nature of the [Fe(LR)2]2+ complexes in solution must reflect a subtle balance of steric and electronic factors involving the ligand ‘R’ substituents.Graphical abstractFour different complexes of the type shown, [Fe(LR)2]2+, have been prepared, with R = methyl, allyl, benzyl and isopropyl. All the compounds are high-spin in acetone solution and the solid state at room temperature and below, except for one salt of [Fe(LMe)2]2+ which is predominantly low-spin at 150 K in the crystal. This contrasts with the parent complex (R = H), which exhibits thermal spin-crossover just below room temperature.Highlights► The syntheses of four 2,6-di(pyrazol-3-yl)pyridine (3-bpp) derivatives bearing pyrazolyl N1 substitutents, and salts of their iron(II) complexes. ► Magnetic measurements and crystal structures show that the complex salts (with one exception) are high-spin between 5 and 300 K. ► The complexes are also high-spin in (CD3)2CO solution between 190 and 300 K. ► Distal substitution of 3-bpp suppresses spin-crossover for all the substituents examined, regardless of their steric and inductive properties.