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Pure Appl. Chem., 2009, Vol. 81, No. 8, pp. 1357-1383

Published online 2009-07-20

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

Roman Boča1, Ivan Nemec1, Ivan Šalitroš1, Ján Pavlik1, Radovan Herchel2 and Franz Renz3

1 Institute of Inorganic Chemistry, Slovak University of Technology (FCHTP), SK-812 37 Bratislava, Slovakia
2 Department of Inorganic Chemistry, Palacký University, CZ-77147 Olomouc, Czech Republic
3 Institute of Inorganic Chemistry, Leibniz University Hannover, D-30167 Hannover, Germany

Abstract: In the dinuclear and polynuclear metal complexes exhibiting the low-spin (LS) to high-spin (HS) transition, the spin-crossover phenomenon interferes with the magnetic exchange interaction. The latter manifests itself in forming spin-multiplets, which causes a possible overlap of the band originating in different reference spin states (LL, LH, HL, and HH). A series of dinuclear Fe(III) complexes has been prepared; the iron centers are linked by a bidentate bridge (CN-, and diamagnetic metallacyanates {Fe(CN)5(NO)}, {Ni(CN)4}, {Pt(CN)4}, and {Ag(CN)2}). Magnetic measurements confirm that the spin crossover proceeds on the thermal propagation. This information has been completed also by the Mössbauer spectral (MS) data. A theoretical model has been developed that allows a simultaneous fitting of all available experimental data (magnetic susceptibility, magnetization, HS mole fraction) on a common set of parameters.