Mixed-metal cluster chemistry. 27. Coupling of diphenylbuta-1,3-diyne and CO at tungsten-triiridium cluster cores

Reactions of WIr₃(CO)₁₁(η-C₅H ₄R) (R=H, Me) and excess diphenylbuta-1,3-diyne in refluxing toluene afford a large number of products in each case, one of which has been identified as [WIr₃{μ ₄-η ⁷-C(Ph)C(C≡ CPh)C(Ph)CC(H)CC₆H₄ C(O)-2}(CO)₇(η-C ₅H₄R)] [R=H (10 %) (1), Me (6 %)] by a single-crystal X-ray diffraction study of 1. The structure of 1 reveals a unique ten-electron-donating ligand which has formed from combination of two diphenylbuta-1,3-diyne units and one carbonyl group, addition of the latter having presumably proceeded by orthometallation of one phenyl group, followed by formal insertion of the carbonyl into the Ir-phenyl linkage. Crystal data for 1.CH₂Cl₂: space group P2₁/n, a = 8.6081(1)Å, b = 39.3638(5)Å, c = 12.3935(2)Å, β = 100.4889(5)°, V = 4129.33(10)ų, Z = 4, R = 0.030, R _w = 0.026 for 4982 reflections [I > 2.00σ(I)].