Cooperative Au _vertex –Au _shoulder Pair Sites of Biicosahedral Au ₂₅ Cluster for Highly Oxidative Carbonylation of Diamine to Cyclic Urea

Abstract

Abstract The realization of target reactants completely transformed on the designed active sites toward desired products remains a challenge. Here, we report that the [Au 25 (PPh 3 ) 10 (SCH 2 CH 2 Ph) 5 Cl 2 ] 2+ cluster in the library of metal clusters is unique for the oxidative carbonylation of diamine to cyclic urea. Our studies reveal that the ligand on–off dynamics in the presence of solvent coupled with diamine can invoke the active function of the vertex and shoulder Au of the [Au 25 (PPh 3 ) 10 (SCH 2 CH 2 Ph) 5 Cl 2 ] 2+ , i.e., that is respectively capped by Cl and PPh 3 . Notably, the transient exposed Au vertex –Au shoulder neighboring sites exhibit a selective recognition to reaction molecules, leading to the interdependent and stepwise reactivity for the oxidative carbonylation of diamine with CO and O 2 . The diamine is preferentially adsorbed on the Au shoulder site, with the CO inserting sequentially into the diamine to produce the key intermediate containing the secondary amide group, and meanwhile the Au vertex site engages in converting O 2 to singlet oxygen and finally enables the H‐atom abstraction from the amine group of the above intermediate, thereby achieving an exclusive selectivity for cyclic urea. This work provides an alternative route for the efficient carbonylation upgrading of diamine, typically distinguished from homogeneous organometallic complexes and heterogeneous supported metal catalysts.