COMPARATIVE REACTIVITY OF TRIRUTHENIUM AND TRIOSMIUM MU(3)-ETA(2)-IMIDOYLS .2. REACTIONS WITH ALKYNES

The reactions of Ru-3(CO)(9)(mu(3)-eta(2)-CH3C=NCH2CH3)(mu-H) (1), M-3 (CO)(9)(mu(3)-eta(2)-C=N(CH2)(3))(mu-H) (M = Ru (2), M = Os (3)) with the alkynes RC=CR (R = CH3, C6H5, CO2Me) have been studied. The ruthen ium complexes 1 and 2 react with 2-butyne at 70 degrees C to give two very different trimetallic alkyne derivatives: ))(mu-eta(2)-CH3C=NCH2C H3)(eta(1)-COC(CH3)C(H)CH3) (5) and (mu(3)-eta(2)-C=N(CH2)(3))(mu-eta( 2)-CH3C(H)=CCH3) (6). The osmium imidoyl 3 does not react with 2-butyn e even at elevated temperatures. However, the reaction of Os-3(CO)(9)( mu-eta(2)-C=N(CH2)(3))(mu-H)(CH3CN) (7b), synthesized from Os-3(CO)(10 )(mu-eta(2)-C=N(CH2)(3))(mu-H) (7a), with 2-butyne yields the analog o f 6, )(8)(mu(3)-eta(2)-C=N(CH2)(3))(mu-eta(2)-RC(H)=CR) (R = CH3 (10), R = C6H5 (11)) on thermolysis of the initially formed nonacarbonyl pr ecursors (8 and 9 for R = CH3), which are a mixture of isomers. Direct reaction of 7a with diphenylacetylene at 100 degrees C gives somewhat lower yields of 11. The reaction of 7b with dimethylacetylenedicarbox ylate or the direct reaction of 3 with this alkyne yields the nonacarb onyl derivative a(2)-C=N(CH2)(3))(mu(3)-eta(3)-CH3O2CC=C(H)CO2CH3) (12 ). Direct reaction of 7a with a 2.5 molar excess trimethylamine N-oxid e at room temperature yields the alkyne-imidoyl-coupled product (mu-et a(6)-CH3C(H)=C(CH3)C(CH3)=C(CH3)C=N(CH2)(3)) (13) The solid state stru ctures of 5, 11, 12, and 13 are reported. A comparative study of the e lectrochemical properties of 5 and 1 is also reported.