Five-Coordinate Complexes MHCl(CO)(PiPr3)2 (M = Os, Ru) as Precursors for the Preparation of New Hydrido− and Alkenyl−Metallothiol and Monothio−β-Diketonato Derivatives

Abstract

The five-coordinate complexes MHCl(CO)(PiPr3)2 (M = Os (1), Ru (2)) react with NaSH to give the unsaturated hydrido−metallothiol derivatives MH(SH)(CO)(PiPr3)2 (M = Os (3), Ru (4)). Complexes 3 and 4 react with CO to afford the cis-dicarbonyl compounds MH(SH)(CO)2(PiPr3)2 (M = Os (5), Ru (6)). Similarly, the reaction of 3 with P(OMe)3 leads to OsH(SH)(CO){P(OMe)3}(PiPr3)2 (7). Treatment of 3 with 1 equiv of acetylenedicarboxylic methyl ester which is the result of the trans addition of the S−H bond of 3 to the carbon−carbon triple bond of the alkyne. The structure of 8 was determined by X-ray investigation. The geometry of the complex can be rationalized as a distorted octahedron with the two phosphorus atoms of the triisopropylphosphine ligands occupying apical positions. The equatorial plane is formed by the bidentate ligand, which acts with a bite angle of 89.49(12)°, the hydrido ligand trans-disposed to the oxygen atom, and the carbonyl group trans-disposed to the sulfur atom. Acetylenedicarboxylic methyl ester also reacts with 4 by insertion of the carbon−carbon triple bond into the S−H bond. However, in the resulting monothio-β-diketonato the hydrido ligand lies trans to the sulfur atom. In solution, complex 9 isomerizes into 10, containing the hydrido ligand trans-disposed to the oxygen atom of the chelate group. The stereochemistry of 10 was corroborated by X-ray investigation. The geometry of 10 is the same as that of 8, and the structural parameters of both molecules are statistically identical. Phenylacetylene and methylpropiolate, in contrast to acetylenedicarboxylic methyl ester, react with 3 and 4 by insertion of the carbon−carbon triple bonds into the M−H bonds to give the unsaturated alkenyl−metallothiol complexes M{(E)-CHCHPh}(SH)(CO)(PiPr3)2 (M = Os (11), Ru (12)) and Ru{(E)-CHCHCO2CH3}(SH)(CO)(PiPr3)2 (13).