Perfluoroalkyl- and perfluoroaryl-amidato derivatives of ruthenium, osmium and iridium

Abstract

Trifluoroacetamide reacted with [RuCl₂(PPh₃)₃]–NEt₃ in boiling toluene to afford the binuclear species [Ru₂(µ-Cl)(µ-H){µ-NHC(O)CF₃}₂(PPh₃)₄]1a(‘head-to-tail’ N,O-amidato bridged isomer). In contrast use of [RuH(Cl)(PPh₃)₃] as the ruthenium precursor led to formation of 1a as a mixture of ‘head-to-tail’ and ‘head-to-head’ isomers plus a small amount of another product 2a which is tentatively formulated as [Ru₂(µ-H){µ-NHC(O)CF₃}₃(PPh₃)₄] with one N- and two N,O-bridging amidate ligands. Carbonylation of these products in boiling toluene yielded dicarbonyl species [Ru₂(µ-Cl)(µ-H){µ-NHC(O)CF₃}₂(CO)₂(PPh₃)₂]3a(‘head-to-tail’ and ‘head-to-head’ isomers) plus a trace of [Ru₂(µ-H){µ-NHC(O)CF₃}₃(CO)₂(PPh₃)₂]4a. Under similar conditions trifluoroacetamide reacted with [RuH₂(CO)(PPh₃)₃], [Ru(CO)₃(PPh₃)₂], [OsH₂(CO)(PPh₃)₃] and mer-[IrH₃(PPh₃)₃] to yield the mononuclear products [Ru{NHC(O)CF₃}₂(CO)(H₂O)(PPh₃)₂]5a, [Ru{NHC(O)CF₃}₂(CO)₂(PPh₃)₂]6a, [OsH{NHC(O)CF₃}(CO)(PPh₃)₃]7a and [IrH₂{NHC(O)CF₃}(PPh₃)₃]8a respectively, all of which contain monodentate N-bonded trifluoroacetamidate ligands. Pentafluoropropionamide and pentafluorobenzamide yielded analogous products 1b, 2b, 3b and 8b, and 1c respectively. The crystal structure of [Ru₂(µ-Cl)(µ-H){µ-NHC(O)C₂F₅}₂(PPh₃)₄]1b has been determined. All other products were characterised by infrared and NMR spectroscopy.