FRAGMENTATION OF 2-PYRIDYL ESTERS GIVES BOTH ETA(2)(C,O)-BOUND AND ETA(2)(C,C)-BOUND KETENE LIGANDS ON CLIR[P(I-PR)(3)](2)

2-Pyridyl esters react with a source of ClIr[Pr(i-Pr)(3)](2) in a net elimination reaction to give eta(2)(C,O)-bound ketene complexes 4 in the case of diaryl- or aryl-(alkyl)-substituted ketenes and eta(2)(C,C)-bound isomers 3 in the case of monosubstituted Ketenes, explainable by invoking an electronic preference for 3 which can be sterically overridden. (4). The mechanism by which 3 or 4 is formed appears to involve the spectroscopically detectable acyl 8, from oxidative addition of Ir(I) to the ester acyl-oxygen bond, followed by metal-induced beta-hydride elimination.