Spin crossover in heterodinuclear iron(III) Schiff-base complexes
Abstract
The reaction of a nickel(II) imidazolate complex [NiL1](H2L1= 5-{o-[5-chloro-2-hydroxyphenyl)phenylmethyleneamino]phenyliminomethyl}imidazole) with iron(III) Schiff-base complexes [FeL2Cl], [FeL3]+ and [FeL4]+[H2L = R(NCHC6H4OH-o)2; R =(CH2)2(L1), (CH2)3NH(CH2)3(L2) or (CH2)3NMe(CH2)3(L3)] yielded the imidazolate-bridged heterodinuclear complexes [FeL2(NiL1)Cl], [FeL3(NiL1)]BPh4 and [FeL4(NiL1)]BPh4, which were characterized by variable-temperature magnetic susceptibility, Mössbauer and ESR spectroscopy. Their spectral and magnetic properties are consistent with high spin/low spin crossover behaviour for the iron(III) atoms. Two analogous copper(II) complexes, [FeL3(CuL1)]BPh4 and [FeL4(CuL1)]BPh4, were also prepared and the latter characterized as an antiferromagnetically coupled copper(II)–high-spin iron(III) system.