Half-sandwich Ru (II) complexes: Effect of ligands on aerobic oxidation of benzylamine

In this study, we compared carbene and pyridine substituted ligands {3-Me-1-[2-(CH2CH2SPh)]-C7H4N2} (L1) and {2-[(2,6-iPr2-C6H3)N=CH]-6-(MeO)C5H3N}(L2) for synthesis of ionic C,S- and N,N-coordinated Ru (II) complexes [(kappa 2-L1)RuCl(eta 6-p-cymene)]+Cl- (1), [(kappa 2-L1)RuI(eta 6-p-cymene)]+I- (2), and [(kappa 2-L2)RuCl(eta 6-p-cymene)]+Cl- (3), respectively. Stannylene ligand [{2,6-(Me2NCH2)2C6H3}SnCl] (L3), as heavy carbene analog, was also used in this study to prepare neutral Sn-coordinated Ru (II) complex [(kappa 1-L3)RuCl2(eta 6-p-cymene)] (4). Finally, reaction of SnCl2 with 1, 3, and 4 was also studied to yield [(kappa 2-L1)RuCl(eta 6-p-cymene)]+[SnCl3]- (5), [(kappa 2-L2)RuCl(eta 6-p-cymene)]+[SnCl3]- (6), and [(kappa 1-L3)RuCl (SnCl3)(eta 6-p-cymene)] (7). The catalytic activity of 1-7 was tested on aerobic oxidation of benzylamine. The effect of different ligands L1-3 as well as the effect of the SnCl3- moiety is discussed. We use different donating systems for half-sandwich Ru (II) complexes to see the effect of ligands on aerobic oxidation of benzylamine.image