Constructing the Transfer Ladder between Active Sites and Functional Units within the Cluster-Based Catalyst for Reductive Amination

Abstract

The remote communication between active sites and the surrounding environment within a heterogeneous catalyst for the orderly bonding of reactive species is highly desired yet very challenging. Here we find that the phosphotungstate with a mesoporous framework (abbreviated as mPTA) has an extraordinary ability to accommodate ammonia but has no activity for catalytic reductive amination, while the Pd3(S-Adm)3(PPh3)3+ (Pd3 for short; S-Adm = 1-adamantanethiol) cluster enables the above reaction but insufficient ammonia occurring on the cluster leads to low activity and inferior selectivity. We thereby construct a transfer channel between the active cluster (Pd3) and the functional unit (mPTA), which is identified as an interfacial ladder of Pd–O–W, delivering ammonia molecules from the functional unit to the active center. The mPTA resembles a pump source to supply ammonia to meet the requirement for the reductive amination over the cluster, in which ammonia hops the ladder to expediently react with H2 and carbonyl compounds awaiting on Pd sites, finally giving rise to remarkable performances with a high yield of amines. We recognize that the interactive cooperation of inner catalysis with peripheral input across two different compounds holds promise in decoupling and controlling complex chemical ecosystems for high-quality productivity.