Cyanide-bridged [Co_2~(II)M~(II)] and [Co _2~(II)M_2~(II)] complexes based on the [Co~(II)(triphos) (CN)_2] building block: Syntheses, structures, magnetic properties, and density functional theoretical studies

摘要

Two families of cationic cyanide-bridged complexes, namely, ([Co(triphos)(CN)_2]_2[M(MeOH)_4]}(ClO _4)_2 ([Co_2M] M = Mn, Fe, Co, and Ni; triphos = 1,1,1-tris((diphenylphosphino)methyl)ethane) and {[Co(triphos)(CN) _2]_2[M(MeOH)_4]_2}(ClO _4)_4 ([Co_2M_2] M = Mn and Ni) have been prepared from reactions of [Co~(II)(triphos)(CN)_2] and M(ClO_4)_2·6H_2O (M = Mn, Fe, Co, Ni) in methanol. The trinuclear complexes [Co_2Mn], [Co_2Fe], and [Co_2Co], as well as both new tetranuclear complexes [Co _2Mn_2] and [Co_2Ni_2], exhibit antiferromagnetic coupling between metal centers. In contrast, the [Co _2Ni] is characterized by ferromagnetic interactions between the Co~(II) and Ni~(II) centers. The magnetic behavior for these complexes was investigated by DFT calculations and was found to derive from overlap patterns of the different magnetic orbitais as influenced by the angles of the cyanide bridges.