Driving diverse bond functionalisation with N-heterocyclic silylene-coinage metal-aryl complexes

Anchoring homolytic and heterolytic bond functionalisation at low-coordinate coinage metal centres is important due to their potential use as active catalysts in organic transformations. In the realm of carbene-stabilised coinage metal chemistry, heteroatom functionalised coinage metal precursors synthesised from such bond activations have long been explored. Interestingly, N-heterocyclic silylene, being an equally potent neutral donor ligand, has not been used for the same. Of note, carbene-stabilised heteroatom functionalised coinage metal precursors are vastly developed with copper centres only, while silver has been underexplored. This work reports the isolation of a variety of [PhC{N( ^t Bu)}₂SiN(SiMe₃)₂] (1) coordinated aryl-copper(i) and aryl-silver(i) complexes (2-8). We have also examined the reactivity pattern of organo-copper with differently substituted silylenes (9-11). These complexes were then utilised to cleave various homolytic and heterolytic bonds to access silylene-coordinated heteroatom functionalised coinage metal complexes (12-24). We have shown the reaction of reactive aryl-coinage metal precursors towards homolytic bonds, having B-B and Se-Se bonds, which led to the formation of an NHSi-supported dimeric μ-boryl bound Cu(i) complex (12) and a new class of unprecedented NHSi-supported coinage metal-selenogenolates (14-16). These aryl-coinage metal precursors also smoothly afforded several elusive NHSi-copper and silver amides (17-22) via N-H bond cleavage. A heterolytic cleavage of the P-Si bond resulted in the formation of NHSi stabilised copper and silver phosphide complexes (23 and 24), among which the latter is the first precedent of the dimeric Ag-phosphide complex. Lastly, we have utilised NHSi → copper-aryl complexes as aryl transfer reagents in C-C coupling reactions, which led to the formation of products in excellent yields with a high TON. The analogous silver complex was employed in the three-component α-aminonitrile synthesis efficiently. Our report establishes NHSi coordinated aryl copper and silver complexes as a perfect and robust platform for accessing a diverse array of reactive coinage metal precursors that were hitherto unknown.