Ruthenium(II) complexes with a new potentially trifunctional phosphinoester and its enolate as ligands

Both RuCl3 . nH(2)O and [RuCl2(PPh(3))(3)] reacted with PBu(t)(CH(2)CO(2)Me)(2) to give a mixture of two isomeric ruthenium(II) complexes [RuCl2{PBu(t)[CH2C(OMe)=O](CH(2)CO(2)Me)-kappa(3)P,O}(2)] 1a and 1b (ratio 3:1) which contain two molecules of the ester as bidentate chelating ligands. Treatment of la,lb with AgPF6 led, after abstraction of one chloride ligand, to the cationic complex [RuCl{PBu(t)[CH2C(OMe)=O](2)-kappa(3)P,O,O}{PBu(t)[CH2C(OMe)=O] [CH(2)CO(2)Me)-kappa(2)P,O}PF6 2 in which one molecule of the phosphinoester is a bi- and the other a tri-dentate ligand. Reaction of 2 with KOBu(1) or NaN(SiMe(3))(2) yielded the neutral phosphinoenolate-ruthenium(II) compound [RuCl{PBu(t)[CH=C(OMe)O][CH2C(OMe)=O]-kappa(3)P,O,O}{PBu(1)[CH2C(OMe)=O](CH(2)CO(2)Me)-kappa(2)P,O}] 3 which, by cleavage of the Ru-O(ester) bonds, reacted with CO or CNMe to give the corresponding monocarbonyl or bis(isocyanide) complexes [RuCl(CO){PBu(t)[CH=C(OMe)O](CH(2)CO(2)Me)kappa(2)P,O}{PBu(t)[CH2C (OMe)=O](CH(2)CO(2)Me)-kappa(2)P,O}] 4 or [RuCl(CNMe)(2){PBu(t)[CH=C(OMe)O](CH(2)CO(2)Me)-kappa(2)P,O}{PBu(t) (CH(2)CO(2)Me)(2)-kappa P}] 5 respectively. On treatment with PhNCO compound 3 underwent ail insertion reaction of the isocyanate into the C-H bond of the metal enolate to give the ring-substituted derivative [RuCl{PBu(t)[C(CONHPh)=C(OMe)O][CH2C(OMe)=O]-kappa(3)P,O,O} {PBu(1)[CH2C(OMe)=O](CH(2)CO(2)Me)-kappa(2)P,O}] 6. While compound 3 reacted with water in tetrahydrofuran to yield almost quantitatively the phosphino(monoester)acetate complex [RuCl{PBu(t)[CH2C(O)O][CH2C(OMe)=O]-kappa(3)P, O,O}{PBu(t)[CH2C(OMe)=O](CH(2)CO(2)Me)-kappa(2)P,O}] 7, reaction of 3 with CNBu(t), in the presence of water, yielded the bis(isocyanide) adduct [RuCl(CNBu(t))(2){PBu(t)[CH2C(O)O](CH(2)CO(2)Me)-kappa(2)P,O}{PBu(t) (CH(2)CO(2)Me)(2)-kappa-P}] 8. Treatment of 3 with HCl or PhSH reconverted the phosphinoenolate into the phosphinoester moiety with concomitant formation of compounds 1a, 1b and [RuCl(SPh){PBu(t)[CH2C(OMe)=O](CH(2)CO(2)Me)-kappa(2)P,O}(2)] 9, respectively. The molecular structures of la and 3 have been determined by X-ray crystallography.