Synthesis, structures, electrochemistry and magnetic properties of a cyano-bridged {Fe2Co2} molecular square

The reaction of tricyanometallate precursor, (Bu4N)[(Tp*)Fe(CN)3] (Tp* = hydrotris(3,5-dimethylpyrazol-l-yl)borate) with Co(ClO4)2·6H2O in the presence of the bidentate dpa (dpa = 2,2′-dipyridyl amine) ligand affords one novel cyano-bridged heterobimetallic {Fe2Co2} molecular square, [FeIII(Tp*)(CN)3]2[CoII(dpa)2]2•2ClO4•4H2O•4CH3OH (1). The molecular structure was determined by single-crystal X-ray diffraction. In compound 1, FeIII ion is coordinated by three cyanide carbon atoms and three nitrogen atoms of Tp* anions. Whereas, the CoII ion is surrounded by two cyanide nitrogen atoms and four nitrogen atoms from two bidentate dpa ligands. Cyclic voltammetry (CV) measurements showed that complex 1 exhibited one quasi-reversible waves (0.1 V vs SCE) in the reduction process, and irreversible waves in the oxidation process. Magnetic measurements indicate that complex 1 exhibits a strong intramolecular ferromagnetic interaction between the low-spin FeIII(S = 1/2) and high-spin CoII(S = 3/2) ions.