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Takemura Y, Nakajima T, Tanase T: Interconversion between ladder-type octanuclear and linear tetranuclear copper (I) complexes supported by tetraphosphine ligands. Dalton Trans. 2009 Dec 14;(46):10231-43. Epub 2009 Oct 16.
Linearly ordered tetraphosphine, meso-bis [(diphenylphosphinomethyl) phenylphosphino] methane (dpmppm), readily reacted with 4 equiv. of CuX in dichloromethane to afford octanuclear copper (I) complexes, [Cu (8)(mu-X)(8)(mu-dpmppm)(2)] (X = Cl (1a), Br (1b), I (1c)), which involve a ladder-type {Cu (8)(mu-X)(2)(mu (3)-X)(6)} core supported by two dpmppm ligands in anti arrangement. Complex 1a was further transformed by treatment with Cu (OTf)(2) into [Cu (8)(mu-X)(6)(OTf)(2)(mu-dpmppm)(2)] (2) in which two TfO anions attached to both end of the Cu (8) ladder. When complexes 1 were dissolved in dimethyl sulfoxide (dmso) in the presence of 2 equiv. of dpmppm, the octacopper (I) ladder was unzipped to result in the linear tetranuclear copper (I) complex, [Cu (4) X (mu-X)(3)(mu-dpmppm)(2)(dmso)] (X = Cl (3a), Br (3b), I (3c)). Similar treatment of dpmppm with 2 equiv. of CuX in the presence of coordinative solvents, N,N'-dimethylformamide (dmf) and pyridine (py), yielded the symmetrical tetracopper (I) complexes, [Cu (4)(mu-Cl)(3)(mu-dpmppm)(2)(dmf)(2)][CuCl (2)] (4) and [Cu (4)(mu-I)(3)(mu-dpmppm)(2)(py)(2)] I (5). A series of tetracopper (I) complexes with terminal isocyanide ligands, [Cu (4)(mu-X)(3)(mu-dpmppm)(2)(RNC)(2)] PF (6) (X = Cl, R = Xyl (6a); X = Br, R = Mes (7b); X = I, R = Xyl (8a), Mes (8b), (t) Bu (8c)), were obtained from reactions of dpmppm with 2 equiv. of CuX in dmf or acetonitrile followed by addition of an excess of RNC and NH (4) PF (6). Complexes 3-8 possess a bending Cu (4)(mu-X)(3) chain supported by two dpmppm ligands in syn arrangement, where the terminal sites are reactive and accommodate a variety of terminal ligands. When complex 8c was treated with AgPF (6) in a CH (3) CN-CH (2) Cl (2) mixed solvent, the soft Lewis acidic Ag (I) ions took the copper (I)-binding dpmppm off and the resultant two {Cu (4)(mu-I)(3)(mu-dpmppm)((t) BuNC)(2)}(+) fragments were zipped up to form the ladder-type octacopper (I) complex, [Cu (8)(mu-I)(6)(mu-dpmppm)(2)((t) BuNC)(2)](PF (6))(2) (9). The apparent interconversion between the Cu (8) ladder and the Cu (4) chain might proceed through a labile intermediate with a {Cu (4)(mu-X)(3)(mu-dpmppm)}(+) unit, which could be useful synthon of further extended copper (I) halide clusters. |
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