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, [Cu-2(bpca)(2-)(H2O)(2)Fe-2(5,5'-dmbipy)(2)(CN)(8)] center dot 2[Cu(bpca)Fe(5,5'-dmbipy)(CN)4] center dot 4H(2)O (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, J(1) = 2.64 cm(-1), J(2) = 5.40 cm(-1) and TIP = -2.36 x 10(-3) for complex 4, and g = 2.17, J = 4.82 cm(-1) and zJ' = 0.029 cm(-1) for complex 5. (C) 2008 Elsevier B. V. All rights reserved.