Diverse and Selective Metal-Ligand Cooperative Routes for Activating Non-Functionalized Ketones.

The rhodium and iridium complexes [CpM(κ,,-)][SbF] (Cp = η-CMe; M = Rh, ; Ir, ; = pyridinyl-amidine ligand) exhibit three different cooperative metal-ligand reactivity modes when interacting with nonfunctionalized ketones. With the methyl ketones CHCOR (R = CH, Ph, CF), activation of the ketone methyl C(sp)-H bond yields ketonyl compounds of formula [CpM(CHCOR)(κ,-)][SbF]. With the ketones (CF)CO and CFCOPh, the complexes add to the C═O double bond of the ketone. The addition of the iridium compound occurs across the metal atom and the exocyclic carbon of the dearomatized pyridinyl moiety, and that of the rhodium analogue takes place through the rhodium atom and the exocyclic methylene carbon of the Cp ligand of the intermediate fulvene complex. In the rhodium case, the resulting metal-alkoxide derivative evolves to give rise to rhodium derivatives containing up to four added ketone molecules. In all of these processes, no additives are required, rendering them atom 100% efficient procedures for bond activation. From a mechanistic point of view, DFT calculation reveals that the diverse and selective behavior of and toward ketones can be explained by invoking three different intermediates, each driving the process through distinct reaction pathways.