Insertion reactions of dimethyl acetylenedicarboxylate with alkenylruthenium complexes of the type [Ru(CO)Cl(R′CCHR)(PPh₃)₂]. The crystal structure of [Ru(CO)Cl{MeOOCCC(CO₂Me)-CHCHCMe₃}(PPh₃)₂]

Reactions between alkenylruthenium complexes of the type [Ru(CO)Cl(R′ CCHR)(PPh3)2] (R′ = R = H, Me, Ph; R′ = H, R = C3H7, CMe3, Ph) with dimethylacetylenedicarboxylate give mixed bis-insertion complexes of formula [Ru(CO)Cl{MeOOCCC(CO2Me)CR′ CHR}(PPh3)2], which have been isolated and characterized only in the case of terminal alkyne derivatives (R′ = H). This reaction is competitive with the simple displacement reaction of the non-activated acetylene by dimethyl acetylene-dicarboxylate. The complexes were characterized by elemental analysis and 1H NMR and IR spectroscopy. The molecular structure of [Ru(CO)Cl{MeOOCCC(CO2Me)CHCHCMe3})2], determined by X-ray diffraction, can be regarded as a distorted octahedral species, in which the butadienyl ligand acts as bidentate through an additional CO Ru bond involving a carboxylate oxygen atom, the atom pairs (P,P), (Cl,C) and (O,C) being in trans positions. © 1987.