Dimethylformamide as a convenient CO source for the facile preparation of rhodium-, iridium- or ruthenium-chlorocarbonyl complexes directly from RhCl3•3H2O, IrCl3•3H2O or RuCl3•3H2O

The anionic complexes [RhCl2(CO)(2)](-), [IrCl2(CO)(2)](-) or [RuCl3(CO)(2)(DMF)](-) can be obtained in high yields (up to 85 %) and in less than GO min by refluxing dimethylformamide solutions of RhCl3. 3H(2)O, IrCl3. 3H(2)O or RuCl3. 3H(2)O. Depending on the metal, the presence of small amounts of water and/or hydrochloric acid greatly accelerates the reduction step. For rhodium, several intermediates have been trapped which allow us to propose a mechanism for this reaction. (C) Academic des sciences/Elsevier, Paris.