Synthesis, characterization and reactivity of arene ruthenium compounds based on 2,2′-dipyridylamine and di-2-pyridylbenzylamine and their applications in catalytic hydrogen transfer of ketones

The synthesis and characterization of cationic arene ruthenium compounds [(η6-p-iPrC6H4Me)RuCl(κ2-dpa)]BF4 (1), [(η6-C6H6)RuCl(κ2-dpa)]BF4 (2), [(η6-p-iPrC6H4Me)-RuCl(κ2-dpb)]BF4 (3), [(η6-p-iPrC6H4Me)RuCl(κ2-dpb)]PF6.CH3OH (4) and [(η6-C6H6)-RuCl(κ2-dpb)]PF6 (5) (arene = C6H6 or p-iPrC6H4Me; dpa = 2,2′-dipyridylamine and dpb = di-2-pyridylbenzylamine) have been described. Reactions of the representative compounds 1 and 3 with NaN3, NaCN, and NH4SCN afforded substitution products [(η6-p-iPrC6H4Me)-Ru(κ2-dpa)(N3)]BF4 (6), [(η6-p-iPrC6H4Me)Ru(κ2-dpa)(CN)]BF4 (7), [(η6-p-iPrC6H4Me)-Ru(κ2-dpa)(NCS)]BF4 (8), [(η6-p-iPrC6H4Me)Ru(κ2-dpb)(N3)]BF4 (9), [(η6-p-iPrC6H4Me)-Ru(κ2-dpb)(CN)]BF4 (10) and [(η6-p-iPrC6H4Me)Ru(κ2-dpb)(NCS)]BF4 (11). The compounds under investigation have been characterized by elemental analyses, spectroscopic and electrochemical studies. Molecular structures of 1, 3, 4 and 5 have been determined crystallographically. The compounds 1–3 and 5 exhibited moderate catalytic activity in the reduction of ketones into corresponding alcohol in absence of a base.

Graphical abstractThe synthesis and characterization of five new cationic arene ruthenium complexes [(η6-C10H14)RuCl(dpaH)]BF4, [(η6-C6H6)RuCl(dpaH)]BF4, [(η6-C10H14)RuCl(bzdpa)]BF4, [(η6-C10H14)RuCl(bzdpa)]PF6.CH3OH and [(η6-C6H6)RuCl(bzdpa)]PF6 (η6-arene = C6H6 or C10H14: dpaH = 2,2′-dipyridylamine and bzdpa = di-2-pyridylbenzylamine) are described. Reactivity of [(η6-C10H14)RuCl(dpaH)]BF4, and [(η6-C10H14)RuCl(bzdpa)]BF4,with various species have been examined and it has been shown that the complexes mentioned above moderately catalyze reduction of ketones into corresponding alcohol in absence of a base.Figure optionsDownload full-size imageDownload as PowerPoint slide