Chemistry of iridium carbonyl cluster complexes. Synthesis, chemical characterization and solid state structure of the mixed-metal carbonyl cluster [PPh4][Ir6(μ-CO)3(CO)12{μ3-Cu(NCMe)}] · CH2Cl2 and its conversion to the dianion [Ir12(CO)26]2-

The cluster [Ir6(CO)15{Cu(NCMe)}]- is obtained by condensation of [Ir6(CO)15]2- with [Cu(NCMe)4]+ at room temperature in tetrahydrofuran. The salt [PPh4][Ir6(CO)15{μ3-Cu(NCMe)}]. CH2Cl2 crystallizes in the monoclinic space group P21/n (non-standard no. 14) with a = 21.146(12), b = 11.512(9), c = 20.450(9) Å, β = 90.58(4)°, and Z = 4; R = 0.038 and Rw = 0.041 for 2175 observed reflections having I ≥ 3σ,(I). The monoanion consists of an octahedron of iridium atoms, face-capped by the CuNCMe group, with twelve terminal carbonyls (two for each iridium atom) and three edge-bridging carbonyls. Average distances (Å) and angles are: IrIr, 2.779; IrCu, 2.636; IrCt, 1.82; COt, 1.18; IrCOt, 173°; IrCb, 2.02; COb, 1.19; IrCOb, 138° (t = terminal, b = edge-bridging). In solution the mixed metal carbonyl cluster decomposes slightly and slowly by loss of copper metal and formation of the previously reported [Ir12(CO)26]2-. © 1992.