Preparation, structural and magnetic characterization of trinuclear and one-dimensional cyanide-bridged Co(III)-Cu(II) complexes

Abstract

By employing two trans-dicyanocobolt(III) building blocks K[Co(bpb)(CN)₂] (bpb^2- = 1,2-bis(pyridine-2-carboxamido)benzenate), K[Co(bpmb)(CN)₂] (bpmb^2- = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate) and one 14-membered macrocycle Cu(II) compound as assembling segment, two cyanide-bridged Co^III-Cu^II complexes {{[Cu(cyclam)][Co(bpb)(CN)₂]}ClO₄}_n·nCH₃OH·nH₂O (1) and {[Cu(cyclam)][Co(bpmb)(CN)₂]₂}·4H₂O (2) (cyclam = 1,4,8,11-tetraazacyclotetradecane) have been successfully prepared and characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single X-ray diffraction analysis shows that complex 1 can be structurally characterized as one-dimensional cationic single chain consisting of alternating units of [Cu(cyclam)]²⁺ and [Co(bpb)(CN)₂]^- with free ClO₄^- as balanced anion, while complex 2 presents cyanide-bridged neutral trinuclear bimetallic structure containing Co₂Cu core, giving clear information that the substitute group on the cyanide precursor has obvious influence on the structure type of the target compound. Investigation over magnetic properties of complex 1 reveals the weak antiferromagnetic coupling between the neighboring Cu(II) ions through the diamagnetic cyanide building block.