Mixed-Metal Cluster Chemistry. 28. Core Enlargement of Tungsten-Iridium Custers with Alkynyl, Ethyndiyl and Butadiyndiyl Reagents

Reaction of [WIr3(μ-CO)3(CO)8(η-C5Me5)] (1c) with [W(CCPh)(CO)3(η-C5H5)] afforded the edge-bridged tetrahedral cluster [W2Ir3(μ4-η2-C2Ph)(μ-CO)(CO)9(η-C5H5)(η-C5Me5)] (3) and the edge-bridged trigonal-bipyramidal cluster [W3Ir3(μ4-η2-C2Ph)(μ-η2-CCHPh)(Cl)(CO)8(η-C5Me5)(η-C5H5)2] (4) in poor to fair yield. Cluster 3 forms by insertion of [W(CCPh)(CO)3(η-C5H5)] into IrIr and WIr bonds, accompanied by a change in coordination mode from a terminally bonded alkynyl to a μ4-η2 alkynyl ligand. Cluster 4 contains an alkynyl ligand interacting with two iridium atoms and two tungsten atoms in a μ4-η2 fashion, as well as a vinylidene ligand bridging a WW bond. Reaction of [WIr3(CO)11(η-C5H5)] (1a) or 1c with [(η-C5H5)(CO)2Ru(CC)Ru(CO)2(η-C5H5)] afforded [Ru2WIr3(μ5-η2-C2)(μ-CO)3(CO)7(η-C5H5)2(η-C5R5)] [R = H (5a), Me (5c)] in low yield, a structural study of 5a revealing a WIr3 butterfly core capped and spiked by Ru atoms; the diruthenium ethyndiyl precursor has undergone RuC scission, with insertion of the C2 unit into a WIr bond of the cluster precursor. Reaction of [W2Ir2(CO)10(η-C5H5)2] with the diruthenium ethyndiyl reagent gave [RuW2Ir2{μ4-η2-(C2CC)Ru(CO)2(η-C5H5)}(μ-CO)2(CO)6(η-C5H5)3] (6) in low yield, a structural study of 6 revealing a butterfly W2Ir2 unit capped by a Ru(η-C5H5) group resulting from RuC scission; the terminal C2 of a new ruthenium-bound butadiyndiyl ligand has been inserted into the WIr bond. Reaction between 1a, [WIr3(CO)11(η-C5H4Me)] (1b), or 1c and [(η-C5H5)(CO)3W(CCCC)W(CO)3(η-C5H5)] afforded [W2Ir3{μ4-η2-(C2CC)W(CO)3(η-C5H5)}(μ-CO)2(CO)2(η-C5H5)(η-C5R5)] [R = H (7a), Me (7c); R5 = H4Me (7b)] in good yield, a structural study of 7c revealing it to be a metallaethynyl analogue of 3.