Neutral and cationic ruthenium(II) complexes with trifunctional phosphane ligands

Compounds of the type [RuCl2(RPX2)(2)] 4-7 (R=iPr, tBu; X=CH2CH2OMe, CH2CO2Me) were prepared by reacting RPX2, with either RuCl3. 3H(2)O or [RuCl2(PPh3)(3)], respectively. In 4-7 the trifunctional phosphanes coordinate as bidentate ligands to the metal center through the phosphorus atom and the oxygen atom of a methoxy or carbonyl group. The lability of the Ru-O bond allows substitution reactions with CO, tert-butylisonitrile and phenylacetylene. The Ru-Cl bonds in 5 (R = tBu; X = CH2CH2OMe) can be cleaved upon treatment with one or two equiv of AgPF6 yielding mono- or dicationic derivatives. In these complexes the ligands are coordinated to the metal center through the phosphorus and both of the oxygen donor atoms. The reaction of the phosphinoesterenolate compound 17 with Ph2C=C=O leads to the insertion of two molecules of the ketene into the C-H bond of one of the five-membered metal-enolate rings to yield the "expanded" chelate complex 18, the structure of which was determined by X-ray crystallography.