CYCLOBUTYNE LIGANDS .2. REACTIONS OF THE CYCLOBUTYNE TRIOSMIUM COMPLEX OS3(CO)9(MU(3)-ETA(2)-C2CH2CH2) (MU-SPH) (MU-H) WITH DIPHENYLACETYLENE

The reaction of the triosmium complex Os3(CO)9(mu3-eta2-C2CH2CH2)(mu-SPh)(mu-H) (1) with diphenylacetylene at 97-degrees-C resulted in the formation of three products: the known compound Os2(CO)6(mu-eta2-C=CHCH2CH2)(mu-SPh) (2) (11% yield) and two new compounds Os3(CO)7[mu-C(Ph)(H)C(Ph)] [(mu-C(Ph)CCH2CH2)(mu3-S) (3) (28% yield) and Os3(CO)7(mu-C(Ph)C(Ph)CCC-H2CH2)(mu-SPh)(mu-H) (4) (25% yield). Both new compounds were characterized by single-crystal X-ray diffraction analysis. Compound 3 contains a sigma-pi coordinated phenylcyclobutenyl ligand formed by the transfer of the phenyl group from the thiolate ligand to the cyclobutyne ligand and a sigma-pi coordinated 1,2-diphenylvinyl ligand formed by the insertion of one molecule of PhC=CPh into the metal-hydrogen bonds. Compound 4 contains a metallacycle formed by the coupling of one molecule of PhC=CPh to the cyclobutyne ligand. Crystal data: for 3a, space group = P2(1)/n, a = 17.401(3) angstrom, b = 7.981(1) angstrom, c = 22.304(4) angstrom, beta = 100.26(1)-degrees, Z = 4, 3048 reflections, R = 0.030; for 4, space group = P1, a = 11.815(2) angstrom, b = 12.260(2) angstrom, c = 11.492(3) angstrom, alpha = 102.91(2)-degrees, beta = 110.86(1)-degrees, gamma = 92.44(1)-degrees, Z = 2, 3274 reflections, R = 0.043.