34156-34-8Relevant academic research and scientific papers
Progressive transmetalation of tetranuclear dioxocopper(II) complexes with cobalt reagents
Henary, Maher,Davies, Geoffrey,Abu-Raqabah, Atieh,El-Sayed, Mohamed A.,El-Toukhy, Ahmed
, p. 1872 - 1879 (2008/10/08)
Aprotic oxidation of tetranuclear copper(I) complexes N4Cu4X4 (I) (N is monodentate N,N-diethylnicotinamide; X is Cl or Br) with dioxygen gives tetranuclear dioxocopper(II) complexes (μ-O)2N4Cu4X4 (II). These targets are transmetalated by excess transmetalators bis(S-methyl isopropylidenehydrazinecarbodithioato)nickel(II) (A) and bis(S-methyl benzylidenehydrazinecarbodithioato)nickel(II) (B) to give isomers of (μ-O)2[NCuNi(H2O)X2]2, Te1 and Te2, respectively. However, if complexes I are first monotransmetalated by A (the metal is Co, Ni, Cu, or Zn) or tris(S-methyl isopropylidenehydrazinecarbodithioato)cobalt(III) (C) and the oxidized, the products are tetramers (μ4-O,μ-O)N3Cu3M(H2O)X 4 (IV). Complexes IV react with excess A (M = Ni) or C to give trimers (μ3-O)N3M3X4 (Tr1) or, when M in IV is Cu (specified as III), with excess A to give the six-member family (μ4-O,μ-O)N3Cu4-x(Ni(H 2O))xCl4 (Te3). It is shown that II (X = Cl) reacts with 1-4 mol of C to give the tetranuclear family (μ-O)2N4Cu4-xCoxCl4 (x = 0-4), which includes the analogue of isomer Te2. Transmetalation of (μ3-O)N3Cu3Cl4 (XIV) with 1-3 mol of C gives the family of Tr1 trimers (μ3-O)N3Cu3-xCoxCl4 (x = 1-3). Structurally different trimers (μ-O)N3(Co,Cu)3Cl4 (Tr2) are obtained by two methods: (1) transmetalation of III with 1-3 mol of C; (2) the four-step sequence (a) transmetalation of I with C and 2 mol of A (M = Cu), (b) oxidation of the product with dioxygen and (c) transmetalation with 1 or 2 mol of C. These two methods give five of the six expected members of the Tr2 family that are distinguishable from Tr1 and from each other by ESR and electronic spectral measurements and by magnetic moment determinations. A trans effect with Co > Cu across μ-oxo bridges influence the course of progressive transmetalations of II and (μ-O)N3(Co,Cu)3Cl4 isomers by C.
