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

Abstract

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 [(κ2‐L1)RuCl(η6‐p‐cymene)]+Cl− (1), [(κ2‐L1)RuI(η6‐p‐cymene)]+I− (2), and [(κ2‐L2)RuCl(η6‐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 [(κ1‐L3)RuCl2(η6‐p‐cymene)] (4). Finally, reaction of SnCl2 with 1, 3, and 4 was also studied to yield [(κ2‐L1)RuCl(η6‐p‐cymene)]+[SnCl3]− (5), [(κ2‐L2)RuCl(η6‐p‐cymene)]+[SnCl3]− (6), and [(κ1‐L3)RuCl (SnCl3)(η6‐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.