Selective Substitution of One of the Substituents on Germanium in Coordinatively Unsaturated Ruthenium Germyl Complexes

The coordinatively unsaturated tri-p-tolylgermyl complex RuCl(Ge[p-tolyl](3))(CO)(PPh3)(2) (1) is obtained in good yield through the reaction between HGe(p-tolyl)(3) and RuCl(Ph)(CO)(PPh3)(2). On treatment of 1 with 1 equiv of NaS2CNR2' (R' = Et, Me), the chloride ligand is displaced and the corresponding coordinatively saturated complexes Ru(kappa(2)-S2CNR2')(Ge[p-tolyl](3))(CO)(PPh3)(2) (2a, R' = Et; 2b, R' = Me) are formed. One of the PPh3 ligands in 2a is labile and undergoes substitution readily on addition of CO to give the cis-dicarbonyl complex Ru(kappa(2)-S2CNEt2)(Ge[p-tolyl](3))(CO)(2)(PPh3) (3). On addition of NaS2CNMe2 to 2b, a PPh3 ligand is displaced by one sulfur atom while the other sulfur atom displaces one of the p-tolyl groups on germanium to give Ru(kappa(2)(Ge,S)-Ge[p-tolyl](2)S2CNMe2)(kappa(2)-S2CNMe2)(CO)(PPh3) (4). Complex 4 is also formed on addition of excess NaS2CNMe2 to 1. Treatment of 1 with pyridine and ethanol under ambient conditions also results in cleavage of one of the germyl p-tolyl groups, and the product formed is the coordinatively unsaturated, ethoxy-substituted germyl complex RuCl(Ge[OEt][p-tolyl](2))(CO)(PPh3)(2) (5). The ethoxy group in 5 is labile, and on contact with n-propanol in solution, alkoxy group exchange slowly occurs to give RuCl(Ge[(OPr)-Pr-n][p-tolyl](2))(CO)(PPh3)(2) (6). This reaction is reversible, and treatment of 6 with ethanol returns S. In a related reaction, treatment of 5 with water gives the hydroxy-germyl analogue RuCl(Ge[OH][p-tolyl](2))(CO)(PPh3)(2) (7). The single-crystal X-ray structures of 1, 2a, 3, and 4 are presented.