Influence of ligand substituent conformation on the spin state of an iron(ii)/di(pyrazol-1-yl)pyridine complex

The temperature of the solution-phase spin-crossover equilibrium in iron(ii) complexes of 4-alkylsulfanyl-2,6-di{pyrazol-1-yl}pyridine (bpp(SR)) complexes depends strongly on the alkylsulfanyl substituent. DFT calculations imply this reflects the conformation of the alkylsulfanyl groups, which lie perpendicular to the heterocyclic ligand donors in [Fe(bpp(StBu))(2)](2+) but are oriented co-planar with the ligand core for smaller SR substituents.

Automated summary

The temperature of the solution-phase spin-crossover equilibrium in iron(ii) complexes of 4-alkylsulfanyl-2,6-di{pyrazol-1-yl}pyridine (bpp(SR)) complexes is strongly dependent on the alkylsulfanyl substituent, which is determined by the conformation of the alkylsulfanyl groups in the complexes.