SYNTHESIS AND CHARACTERIZATION OF ENYNYL, VINYL AND ACETYLIDE COMPLEXES OF OSMIUM(II)

Treatment of [OsH(2)L(4)] [L = P(OEt)(3) or PPh(OEt)(2)] first with CF(3)SO(3)Me and then with an excess of terminal alkynes RC-CM (R = Bu(t), Ph or p-MeC(6)H(4)) produced enynyl derivatives [Os{eta(3)-RC(3)C(H)R}L(4)](+) 1-3. Sequential reactions of [OsH(2)L(4)] with CF(3)SO(3)Me and activated alkynes R'O2CC=CH (R' = Me or Et) or MeO(2)CC=CCO(2)Me yielded alkenyl [Os{CH=C(H)CO(2)R')L(4)](+) 4,5 and [Os{C(CO(2)Me)=C(H)CO2- Me}L(4)](+) 6 cations, respectively. Spectroscopic data (IR, H-1, P-31, C-13 NMR) suggest, in the case of L = P(OEt)(3), the presence of two isomers for the alkenyls 4 and 5, with five- and four-membered, chelate rings of the vinyl ligand. Hydride-alkynyl [OsH(C=CPh)L(4)] complexes were also obtained by treating[OsH(2)L(4)] with CF(3)SO(3)Me followed by treatment with lithium phenylacetylide.