Formation of Di- and tricarbonylruthenium(O) species from (RuH2(CO)(PPh3)3) via decarbonylation of methyl benzoates. X-ray crystal structures of (Ru(CO)2(PPh3)3) and (Ru(O2)(CO)2(PPh3)2)

Dihydridoruthenium(II) complex (RuH2(CO)(PPh3)3) (1) reacts with methyl benzoate in the presence of an olefin at 110degC to afford some dicarbonylruthenium(O) species (Ru(CO)2(PPh3)3) (2) and 'Ru(CO)2(PPh3)2L' (L = the olefin or the ester). A tricarbonylruthenium(O) complex (Ru(CO)3(PPh3)2) (3) is formed at higher reaction temperature. The experiment using 13C-enriched methyl benzoate reveals that the second and the third carbonyl ligands are mainly derived by subtraction of the carbonyl group from the ester. When the reaction is carried out in the presence of triethoxyvinylsilane, a part of the second and the third carbonyl groups is derived from the ethoxy group of the silane, because 1 reacts with the silane at 110degC in the absence of the ester to afford 2 and 3. The formation ratio of 2 and 3 is affected by the type of olefins used; selective formation of 2 and 3 is achieved when triethoxyvinylsilane is used, whereas allylbenzene or cyclooctene affords merely a mixture of the di- and tricarbonyl species. The reaction mixture containing 2 and 'Ru(CO)2(PPh3)2L' is exposed to air to give a peroxo complex (Ru(η2-O2)(CO)2(PPh3)2) (4) smoothly. The molecular structures of 2 and 4 are determined by the single crystal X-ray diffraction method. The complex 2 has a distorted trigonal bipyramidal coordination geometry with two equatorial CO ligands, whereas the complex 4 has a distorted octahedral structure. (author)