Reactions of Cyclometalated Oxazoline Half-Sandwich Complexes of Iridium and Ruthenium with Alkynes and CO

The ligand 4,4-dimethyl-2-oxazolinylbenzene is easily cyclometalated by [IrCl2Cp*]2 or [RuCl(MeCN)2(p-cymene)]PF6 in the presence of sodium acetate. In the case of iridium the resultant complex dissolves in acetonitrile in the presence of KPF6 to give an acetonitrile-coordinated cationic complex. The analogous complex is formed directly in the ruthenium cyclometalation reaction. These labile cationic complexes undergo insertion reactions with internal and terminal alkynes. Internal alkynes give only monoinsertion products, whereas terminal alkynes give mono- or di-insertion products. The cations will also react with CO, but no insertion occurs in this case.