Theoretical Study of Hydrogenation Catalysis of Phosphorus Compound and Prediction of Catalyst with High Activity and Wide Application Scope

Catalysis of phosphorus compound 10-P-3(2)3,7-di(tert-butyl)-5-aza-2,8-dioxa-l-phosphabicyclo[3.3.0]octa-2,4,6-triene 1P and its analogues in transfer hydrogenation of azobenzene with ammonia-borane (NH3BH3) using DFT, CCSD(T), and ONIOM(CCSD(T):MP2) methods. Theoretical calculations clearly reveal that this transfer hydrogenation reaction occurs through the phosphorus ligand cooperative catalysis function with a change in the phosphorus oxidation state between +I and +III. It is noteworthy that the change in phosphorus oxidation state is a characteristic feature of the cooperative catalysis by 1P: it is not easy for a main -group element to change its oxidation state. This characteristic feature differs from that of metal ligand cooperative catalysis in which the metal oxidation state does not change. Theoretical calculations also disclose that the catalytic activity of IP-like compound is improved by introducing electron -withdrawing substituents to the ligand and using the conjugated planar framework of the ligand. The best catalyst here is predicted to be active for transfer hydrogenations of various ketones and acetaldehyde with NH3BH3, indicating that IP-like compound exhibit a wide application scope as a catalyst.