Syntheses, structures, and magnetic properties of heterobimetallic complexes based on tetracyanometallic building blocks

Two tetracyanometalate building blocks, [Fe(5,5′-dmbipy)(CN)4]− (2) and [Fe(4,4′-dmbipy)(CN)4]− (3) (5,5′-dmbipy = 5,5′-dimethyl-2,2′-bipyridine; 4,4′-dmbipy = 4,4′-dimethyl-2,2′-bipyridine), and two cyano-bridged heterobimetallic complexes, [Cu2(bpca)2(H2O)2Fe2(5,5′-dmbipy)2(CN)8] · 2[Cu(bpca)Fe(5,5′-dmbipy)(CN)4] · 4H2O (4) and [Cu(bpca)Fe(4,4′-dmbipy)(CN)4]n (5) (bpca = bis(2-pyridylcarbonyl)amidate), have been synthesized and structurally characterized. Complex 4 contains two dinuclear and one tetranuclear heterobimetallic clusters in an asymmetric unit whereas the structure of complex 5 features a one-dimensional heterobimetallic zigzag chain. The Cu(II) ion is penta-coordinated in the form of a distorted square-based pyramid. Magnetic studies show ferromagnetic coupling between Cu(II) and Fe(III) ions with g = 2.28, J1 = 2.64 cm−1, J2 = 5.40 cm−1 and TIP = −2.36 × 10−3 for complex 4, and g = 2.17, J = 4.82 cm−1 and zJ′ = 0.029 cm−1 for complex 5.