Syntheses, crystal structures and magnetic properties of two cyanide-bridged molecular squares M2II-Co2II (M = Ru, Os) based on the diamagnetic cyanidometal M(dppm)2(CN)2

Two tetra-nuclear cyanide-bridged molecular square complexes [M-II(dppm)(2)(CN)(2)((CoCl2)-Cl-II)](2) (M = Ru, 1; M = Os, 2) (dppm = bis(diphenylphosphino) methane) were synthesized and characterized by elemental analysis, IR, electronic absorption spectra and single-crystal X-ray diffraction analysis. Both the isostructure complexes 1 and 2 crystallize in monoclinic space group P21/c, and possess two cis-M(dppm)(2)(CN)(2) (M = Ru, 1; M = Os, 2) and two CoCl2 units through cyanido bridges. What's more, the environment around the Co(II) atoms in 1 and 2 define a slightly distorted tetrahedron, and are coordinated by two nitrogen atoms from the cyanide groups with cis-configuration and by two chlorine atoms. Temperature dependence of magnetic susceptibilities show both 1 and 2 are weak antiferromagnetic coupling between the paramagnetic Co(II) ions across a diamagnetic cyanidometal -NC-M(II)-CN- bridge. Furthermore, complex 1 exhibits spin-canted behavior. However, there is no such magnetic behavior in complex 2, which may result from the more diffuse nature of the 5d orbits with respect to 4d. (C) 2014 Elsevier Ltd. All rights reserved.