Oxidative addition of iodine, iodomethane and iodobenzene to the rhodium phosphino enolate complex [Rh{Ph2PCH-C(-O)Ph}(CO)(PPh3)] and carbon monoxide insertion into the resulting Rh-carbon bond of [Rh{Ph2PCH-C(-O)Ph}Me(I)(CO)(PPh3)]

The oxidative addition of homo- and heteronuclear molecules XI (X = I, Me, Ph) to the square planar rhodium phosphino enolate complex [Rh{Ph2PCH (-) triple over dot C((-) triple over dot O)Ph}(CO)(PPh3)] 1 afforded the hexacoordinate Rh(III) complexes [Rh{Ph2PCH (-) triple over dot C((-) triple over dot O)Ph}X(I)(CO)(PPh3)] (X = Me 2; X = Ph 3; X = I 4). Complex 2 undergoes CO insertion into the Rh-Me bond to afford three isomers of the acetyl species [Rh{Ph2PCH (-) triple over dot C((-) triple over dot O)Ph}{C(O)Me}(I)(Co)(PPh3)] 5a-c. Two of these isomers lose acetyl iodide to regenerate 1 and these transformations were followed by NMR and IR spectroscopic methods. The reaction of 1 with acetyl chloride results in rapid formation of the acetyl complex [Rh{Ph2PCH (-) triple over dot C((-) triple over dot O)Ph}{C(O)Me}(Cl)(CO)(PPh3)] 6. When left in solution, 6 isomerizes to give two additional isomeric acetyl species. All three isomers rapidly decompose to a Rh(I) species. The crystal structures of 1-3 have been determined by X-ray diffraction. The coordination geometry around the rhodium atom of 2 and 3 is distorted octahedral and the alkyl and halide ligands are in a mutually trans position.