ALKYNE-SUBSTITUTED CARBONYL CLUSTERS OF IRIDIUM - SYNTHESIS, CHARACTERIZATION, AND SOLID-STATE STRUCTURES OF IR6(CO)13(MU-CO)(MU-3-ETA-2-PHCCPH) AND IR6(CO)12(MU-3-ETA-2-PHCCPH)2.CH2CL2

The carbonyl cluster Ir6(CO)14(mu-3-eta-2-PhCCPh) (1) is obtained by oxidation of [Ir6(CO)15]2- with the [Fe(C5H5)2]+ cation, in the presence of diphenylacetylene. Complex 1 crystallizes in the triclinic space group (No.2) P1BAR with alpha = 9.443 (1) angstrom, b = 16.622 (1) angstrom, c = 21.560 (3) angstrom, alpha = 89.87 (1)-degrees, beta = 96.45 (1)-degrees, gamma = 101.78 (1)-degrees, V = 3291 (1) angstrom 3, and Z = 4; R = 0.034 for 6236 observed reflections having I greater-than-or-equal-to 3-sigma(I). When complex 1 is heated with excess of PhC = CPh, a further substitution occurs, yielding the carbonyl cluster Ir6(CO)12(mu-3-eta-2-PhCCPh)2 (2). Crystals of 2 are monoclinic, space group C2/c (No. 15) with a = 10.751 (6) angstrom, b = 17.393 (7) angstrom, c = 23.240 (7) angstrom, beta = 85.42 (4)-degrees, V = 4332 (5) angstrom 3, and Z = 4; R = 0.028 for 1645 observed reflections having I greater-than-or-equal-to 3-sigma(I). Both compounds contain an octahedron of iridium atoms, with the alkynyl units interacting with the faces of the metallic cores, in a mu-3-eta-2 fashion.