Rhodium(I) complexes containing the enolate of N-acetyl-3-butanoyltetramic acid (Habta) and the crystal structure of [Rh(abta){P(OPh)(3)}(2)]

Reaction of N-acetyl-3-butanoyltetramic acid (Habta) (N-acetyl-3-butanoyl-1,5-dihydro-4-hydroxy-2H-pyrrol-2-one) with [Rh(acac)(CO)(2)] (acac = acetylacetonate) in a 1:1 ratio gave [Rh(abta)(CO)(2)] 1 which underwent displacement of CO by either P(OPh)(3) or PPh(3) to give [Rh(abta)(CO)L] [L = P(OPh)(3) or 2 PPh(3) 4] and [Rh(abta){P(OPh)(3)}(2)] 3; the reaction of 4 with PPh(3) gave the five-co-ordinate complex [Rh(abta)(CO)(PPh(3))(2)] 5. The solid-state structure of 3 has been determined by X-ray diffraction. It shows that rhodium adopts a slightly distorted square-planar geometry with the abta enolate ligand adopting an O,O' mode of co-ordination via the functionalities associated with C-4 and the acyl group at C-3 in the pyrrolidine ring. Under (CO)-C-13, 3 is in equilibrium with 2 and 1 as shown by C-13 NMR spectroscopy. No evidence has been found for the formation of five-co-ordinate complexes through the addition of P(OPh)(3) to 2.