Cluster Assisted Formation of Carbon-Carbon Bonds : Synthesis and Crystal Structures of Two Trinuclear Heterometallic Complexes CpWRu₂(CO)₇(μ-H)[OC(NMe₂)CCHCHEt] and CpWRu₂(CO)₆(μ-H)[OC(NMe₂)CCH(μ-η²-C₆H₄)]

Treatment of the carbamoyl cluster Ru₃(CO)₁₀(μ-H)(μ-η²-OC(NMe₂)] with a two molar excess of CpW(CO)₃C≡Cⁿ Pr in refluxing toluene produced a heterometallic cluster complex CpWRu₂(CO)₇(μ-H)[OC(NMe₂) CCHCHEt] (II), whereas the heterometallic clusters CpWRu₂(CO)₆(μ-H)[OC(NMe₂)CCH(μ-η²-C₆H₃X)] (IVb, X=H;IVc, X=Me;IVd, X=F) were isolated from the reactions with CpW(CO)₃C≡CC₆H₄X under similar conditions. Both complexes II and IV were generated via a complicated sequence involving hydride migration to the acetylide, fragmentation of the cluster via removal of a Ru(CO)_n unit, coupling with the carbamoyl ligand and C-H bond activation at the substituent. Crystal data for II: space group R {Mathematical expression};a=26.605(3), c=17.934(2) Å, Z=18; final R_F=0.032, R_w=0.034 for 2720 reflections with I>2σ(I). Crystal data for IVb: space group C 2/c;a=16.120(6), b=14.972(2), c=18.872(4) Å, β=95.46(2)°, Z=8; final R_F=0.0375, R_w=0.0375 for 2074 reflections with I>3σ(I).