Influence of S-Aryl Groups in the Coordination and Reactivity of (nido-Thiocarborane)ruthenium Complexes

Abstract

The reaction of [RuCl2(PPh3)3] and [NMe4][7,8-(SPh)2-7,8-C2B9H10] in ethanol yields [RuCl(7,8-(SPh)2-7,8-C2B9H10)(PPh3)2]·CH2Cl2 (1). The structure of 1 has been determined by crystallographic studies. The crystal contains the two isomers 1a and 1b in a ratio of ca. 3:1. In both isomers the metal has an octahedral geometry and the carborane ligand tricoordinates the Ru(II) center by means of S−Ru, B(11)−H−Ru, and B(2)−H−Ru bonds. Two PPh3 groups and a chloride ligand fulfill the coordination sphere of the metal. The two isomers arise from two different dispositions of the [RuCl(PPh3)2]+ fragment with regard to the carborane cluster. The preference for two agostic B−H−Ru bonds rather than a second S−Ru bond appears to be due to steric factors. The reaction of [RuCl2(PPh3)3] and the cesium or tetramethylammonium salts of [7-(SPh)-8-R-7,8-C2B9H10]- (R = Me, Ph) yields [RuCl(7-SPh-8-R-7,8-C2B9H10)(PPh3)2] (2, R = Me; 3, R = Ph). NMR spectroscopic analyses of 2 and 3 also indicate the presence of isomers analo...