REGIOSPECIFIC COUPLING OF COORDINATED ACETYLIDE AND DISUBSTITUTED ALKYNES - X-RAY STRUCTURES OF CPWOS2(CO)7[C(TOL)C(TOL)CCNBU] AND CPWOS2(CO)7[C(CF3)C(CF3)CCPH]

Treatment of the acetylide complexes CpWOs2(CO)8(CCR), Cp = C5H5, R = Ph, (1) and R = nBu, (2), with Me3NO in acetonitrile followed by reaction with various disubstituted alkynes, C2R′2, in refluxing toluene to give two isomeric trinuclear complexes, CpWOs2(CO)7[C(R′)C(R′)CCR], R = Ph, R′ = Tol, (3); R = nBu, R′ = Tol, (4); R = Ph, R′ = CO2Et, (5); R = nBu, R′ = CO2Et, (6); R = Ph, R′ = CF3, (7) by acetylide-alkyne coupling is described. The structure of each isomeric complex consists of a WOs2 triangle and a coordinated C4 hydrocarbyl fragment, established by single-crystal X-ray diffraction studies on 4 and 7. The possible mechanism for the formation of these two coupling products is discussed. Crystal data for 4: space group P21/c; a = 14.21(1), b = 10.80(1), c = 21.46(2) Å, β = 97.82°, Z = 4; final R = 0.0541, Rw = 0.0469 and GOF = 2.228. Crystal data for 7: space group P21/c; a = 10.446(6), b = 18.08(1), c = 14.437(8) Å, β = 105.66(4)°, Z = 4; final R = 0.0595, Rw = 0.0512 and GOF = 3.307. © 1990.