Abstract
Proton-coupled 13C NMR studies of vinyl complexes obtained by insertion of MeO2CCCCO2Me into the Ru–H bond of [Ru(CO)2Cl(H)L2](L = PMe2Ph or AsMe2Ph) or one Ru–H bond of [Ru(CO)2H2L2] have shown that the reactions involve trans addition of Ru–H to the alkyne. For the PMe2Ph complexes, selective deuteriation was required to simplify the spectra. In contrast, [Ru(CO)Cl(H)(PMe2Ph)3] reacts by cis addition of Ru–H to the alkyne. Carbonyl substitution in [Ru(CO)2{C(CO2Me)C(CO2Me)H}Cl(PMe2Ph)2] by PMe2Ph leaves the geometry of the vinyl ligand unchanged, so that two (non-interconverting) isomers of [Ru(CO){C(CO2Me)=C(CO2Me)H}Cl(PMe2Ph)3] can be obtained. Whereas trans-[Ru(CO)2Cl2(PMe2Ph)2] combines with MeO2CCCCO2Me by cis addition of Ru–Cl to the alkyne, [Ru(CO)(η2-C2H4)Cl2(PMe2Ph)2] apparently reacts by trans addition, yielding [[graphic omitted]OMe)Cl}Cl(PMe2Ph)2]. Since, however, both reactions appear to involve the same ruthenium intermediate, [Ru(CO)Cl2(PMe2Ph)2], it is possible that the direction of addition is the same in both cases, but that the vinyl ligand can isomerize.
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