Chemistry of iridium carbonyl cluster complexes. Synthesis, chemical characterization and solid state structure of the mixed-metal carbonyl cluster [PPh 4][Ir 6(μ-CO) 3(CO) 12{μ 3-Cu(NCMe)}] · CH 2Cl 2 and its conversion to the dianion [Ir 12(CO) 26] 2−

Abstract

The cluster [Ir 6(CO) 15{Cu(NCMe)}] − is obtained by condensation of [Ir 6(CO) 15] 2− with [Cu(NCMe) 4] + at room temperature in tetrahydrofuran. The salt [PPh 4][Ir 6(CO) 15{μ 3-Cu(NCMe)}]. CH 2Cl 2 crystallizes in the monoclinic space group P2 1/ 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 R w = 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: IrIr, 2.779; IrCu, 2.636; IrC t, 1.82; CO t, 1.18; IrCO t, 173°; IrC b, 2.02; CO b, 1.19; IrCO b, 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 [Ir 12(CO) 26] 2−.