The unexpected role of CO in C-H oxidative addition by a cationic rhodium(I) complex

(Chemical Equation Presented) CO(mpletely) unexpected: The oxidative addition of C-H bonds to transition-metal ions usually requires high electron density at the metal center, and therefore strong π-acceptor ligands, such as carbon monoxide, are normally expected to inhibit such reactions. Hence surprisingly, an electron-poor cationic Rh^I system is observed in which addition of a CO ligand can actually promote oxidative addition of a strong C-H bond (see scheme).