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

Boča, Roman; Nemec, Ivan; Šalitroš, Ivan; Pavlik, Ján; Herchel, Radovan; Renz, Franz

doi:10.1351/PAC-CON-08-07-20

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

http://dx.doi.org/10.1351/PAC-CON-08-07-20

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.