Hydrogenation and isomerization reactions in the addition of carboxylic acids containing alkyne or alkene groups to RuClH(CO)(PPh3)3

The reaction of the complex [RuClH(CO)(PPh3)(3)] with alkynecarboxylic acids (HO2CC=CR; R = Ph and Me) gives the complexes [RuCl(O2CCH=CRH) (CO) (PPh3)(2)], which contain an eta(2)-alkenecarboxylate ligand. The same type of compounds with R = Me can be obtained from the reaction of [RuClH(CO)(PPh3)(3)] with allylacetic acid (HO2CCH2CH=CH2), which is isomerized to a 2-buten-1-carboxylate ligand. The reaction of [RuClH(CO)(PPh3)(3)] with 4-pentynoic acid (HO2CCH2CH2C=CH) produces the compound [RuCl(O2CCH2CH2CH=CH2)(CO) (PPh3)(2)], which contains an eta(2)-carboxylate ligand resulting from the hydrogenation of the alkyne group. Possible reaction mechanisms of hydrogenation and isomerization are discussed. (C) 1998 Elsevier Science S.A. All rights reserved.