CLUSTERS CONTAINING CARBENE LIGANDS .11. CARBENE LIGAND TRANSFER - REACTION OF OS3(CO)11[C(ET)NME2] WITH TERMINAL ALKYNES

The reaction of Os3(CO)11[C(Et)NMe2] (1) with Bu(t)C2H in the presence of Me3NO has yielded the new complex Os3(CO)9[C(Et)NMe2][mu-3-C(H)CBu(t)] (3) in 22% yield and the known complex Os3(CO)10[mu-H2CNMeC(Et)](mu-H) (2) in 14% yield. When refluxed in hexane solvent for 1.5 h, compound 3 was converted to the three new complexes Os3(CO)8[C(Et)NMe2][mu-3-CCBu(t)](mu-H) (4; 35%), Os3(CO)8[C(Et)N(Me)CH2][mu-3-CHCBu(t)](mu-H) (5; 43%), and Os3(CO)9[mu-3-Bu(t)CC{C(Et)(NMe2)}](mu-H) (6a; 8%). The reaction of 1 with PhC2H in the presence of Me3NO yielded Os3(CO)9[mu-3-PhC2C(Et)(NMe2)](mu-H) (6b; 35%). Compound 5 was converted back to 3 (9%) with the formation of some 4 (7%) by reaction with CO at 68-degrees-C/1 atm. Compound 4 was converted to 6a (60%) by reaction with CO at 102-degrees-C/1000 psi, but no 6a could be obtained from 4 under the original reaction conditions. The phenyl derivative 6b was also obtained in 35% yield from the reaction of 1 with PhC2H at 97-degrees-C without addition of Me3NO. Compounds 3-5 and 6b were characterized by single-crystal X-ray diffraction analysis. Compound 3 contains a triply bridging BU(t)C2H ligand and a terminally coordinated ethyl(dimethylamino)carbene ligand. Compound 4 contains a triply bridging tert-butylacetylide ligand, terminally coordinated ethyl(dimethylamino)carbene, and a hydride ligand. Compound 5 contains a triply bridging Bu(t)C2H ligand, a hydride, and an ethyl(dimethylamino)carbene ligand that was metalated on one of the N-methyl groups. Compound 6b contains a triply bridging phenyl(ethyl(dimethyliminio)methyl)alkyne ligand that was formed by the transfer of the carbene ligand to the alkyne ligand. Crystal data: for 3, space group P2(1), a = 8.648 (3) angstrom, b = 12.039 (5) angstrom, c = 12.084 (2) angstrom, beta = 97.18 (2)-degrees, Z = 2,1748 reflections, R = 0.025; for 4, space group P2(1)/n, a = 10.755 (2) angstrom, b = 14.669 (4) angstrom, c = 15.841 (3) angstrom, beta = 96.64 (2)-degrees, Z = 4, 2074 reflections, R = 0.030; for 5, space group P2(1)/n, a = 8.623 (4) angstrom, b = 23.836 (4) angstrom, c = 11.925 (3) angstrom, beta = 99.92 (1)-degrees, Z = 4, 2705 reflections, R = 0.031; for 6b, space group P2(1)/n, a = 9.027 (3) angstrom, b = 16.051 (4) angstrom, c = 17.769 (3) angstrom, beta = 93.17 (1)-degrees, Z = 4, 1804 reflections, R = 0.035.