Interplay between spin crossover and exchange interaction in iron(lll) complexes

Abstract

In the dinuclear and polynuclear metal complexes exhibiting the low-spin (LS) tohigh-spin (HS) transition, the spin-crossover phenomenon interferes with the magneticexchange interaction. The latter manifests itself in forming spin-multiplets, which causes apossible overlap of the band originating in different reference spin states (LL, LH, HL, andHH). A series of dinuclear Fe(III) complexes has been prepared; the iron centers are linkedby a bidentate bridge (CN~, and diamagnetic metallacyanates {Fe(CN)5(NO)},{Ni(CN) 4}, {Pt(CN)4}, and {Ag(CN)2}). Magneticmeasurements confirm that the spin crossover proceeds on the thermal propagation. Thisinformation has been completed also by the Mossbauer spectral (MS) data. A theoreticalmodel has been developed that allows a simultaneous fitting of all available experimentaldata (magnetic susceptibility, magnetization, HS mole fraction) on a common set ofparameters. © 2009 IUPAC.