Spin-crossover in a trans-[FeL2(NCS)2] family (L = triaryltriazole): remote substituent effects on spin transition modes and temperature†
Abstract
We report the syntheses, characterisations, and spin-crossover behaviours of four mononuclear trans-[Fe(L1–L4)2(NCS)2] complexes (L = 4-(p-R1-phenyl)-3,5-bis(2-pyridyl)-4H-1,2,4-triazole and 4-(p-methylphenyl)-3-(p-R2-phenyl)-5-(2-pyridyl)-4H-1,2,4-triazole, (1) R1 = Cl (L1); (2) R1 = Me (L2); (3) R2 = MeO (L3); (4) R2 = F (L4)). The X-ray single crystal structural analysis reveals that 1 and 2 crystallize in the triclinic space group P, whereas 3·0.5H2O and 4 crystallize in the monoclinic space group P21/c, and all complexes possess a similar distorted [FeN6] octahedron with two trans-positions NCS− anions. Changing of the distal substituent on the