Syntheses and crystal structures of four cyanide-bridged trinuclear iron(III)-copper(II)-iron(III) complexes exhibiting abnormal antiferromagnetic coupling

摘要

Four heterobimetallic trinuclear Fe-D-Cu-II-Fe-D complexes [Cu(cyclam)][Fe(bpb)(CN)(2)](2)center dot 4H(2)O (1), [Cu(cyclam)][Fe(bpClb)(CN)(2)](2)center dot 4H(2)O (2), [Cu(cyclam)][Fe(bpmb)(CN)(2)](2)center dot 4H(2)O (3) and [Cu(cyclam)][Fe(bpdmb)- (CN)(2)](2)center dot H2O (4) (cyclam = 1,4,8,11-tetraazacyclotetradecane, bpb(2-) = 1,2-bis(pyridine-2-carboxamido), bpClb(2-) = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate, bpmb(2-) = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, bpdmb(2-) = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate) have been synthesized based on cyanide-containing building blocks [Fe(L)CN2](-) (L = bpb(2-), bpClb(2-), bpmb(2-) and bpdmb(2-)) and [Cu(cyclam)](2+). Their structures and magnetic properties were investigated. The single-crystal X-ray diffraction analyses reveal that they are all neutral trinuclear sandwich-like structures. Magnetic investigations show that they are all abnormal antiferromagnetic, with J = -0.95 cm(-1) for 1, -0.70 cm(-1) for 2, -0.93 cm(-1) for 3 and -0.85 cm(-1) for 4 based on the Hamiltonian Acurrency sign = -2 JAe (Cu)(Ae (Fe(1)) + Ae (Fe(2))). The abnormal antiferromagnetic coupling between Fe(III) and Cu(II) in the four complexes can be attributed to the small Cu-Na parts per thousand C bond angles.