Group 13 metalloligands regulate bimetallic [Pd-E] (E = Al, Ga, In)-catalyzed CO₂ hydrosilylation: mechanism and...

Group 13 metalloligands can regulate catalytic performance through their heterobimetallic bonds and have found widespread applications in catalysis. Herein, the detailed mechanism of CO₂ hydrosilylation catalyzed by 6,6″-bis(phosphino)terpyridine-coordinated heterobimetallic [Pd-E] (E = Al, Ga, and In) catalysts was investigated using DFT calculations. The computational results reveal that Cs-pivalate initially reacts with the [Pd-E] (E = Al, Ga, and In) scaffold to generate the key intermediate A, which activates the Si-H bond in HSiMe₂Ph to generate a Pd-H species; the final product is obtained after CO₂ insertion into the Pd-H bond, followed by a second Si-H bond activation coupled with Si-O bond formation. In [Pd-E], Pd is the active site, and the Group 13 E atom modulates the charge distribution on Pd through the Pd-E bonding interaction. The different catalytic activities of [Pd-E] (E = Al, Ga, and In) may come from the formation of A through the reaction of [Pd-E] with Cs-pivalate, and the electron-deficient nature of E promotes its reaction with Cs-pivalate to facilitate the formation of intermediate A, thereby conferring excellent catalytic activity upon the [Pd-Al] catalyst. The calculated barriers predict [Pd-Ga] and [Pd-In] to be at least as competent as [Pd-Al] after the formation of A. Based on the bonding analysis and potential energy surface profiles, the bimetallic [Ni-Al] species is theoretically predicted to be an efficient catalyst for CO₂ hydrosilylation.