Multi-active Site Dynamics on a Molecular Cr/Co/Se Cluster Catalyst

This study provides detailed insights into the interconnected reactivity of the three catalytically active sites of an atomically precise nanocluster Cr3(py)3Co6Se8L6 (Cr3(py)3, L = Ph2PNTol–, Ph = phenyl, Tol = 4-tolyl). Catalytic and stoichiometric studies into tosyl azide activation and carbodiimide formation enabled the isolation and crystallographic characterization of key metal-nitrenoid catalytic intermediates, including the tris(nitrenoid) cluster Cr3(NTs)3, the catalytic resting state Cr3(NTs)3(CNtBu)3, and the mono(nitrenoid) cluster Cr3(NTs)(CNtBu)2. Nitrene transfer proceeds via a stepwise mechanism, with the three active sites engaging sequentially to produce carbodiimide. Comparative structural analysis and CNtBu bind-ing studies reveal that the chemical state of neighboring active sites regulates the affinity for substrates of an individual Cr-nitrenoid edge site, intertwining their reactivity through the inorganic support.