Silyl(silylene) Coinage Metal Complexes Obtained from Isolable Cyclic Alkylsilylenes

A series of coinage metal complexes ligated by cyclic alkylsilylenes (3M and 4M; M = Cu, Ag, Au) were synthesized by the reaction of the corresponding cyclic alkylsilylene, i.e., cyclic dialkylsilylene (CDASi) 1 or cyclic alkylaminosilylene (CAASi) 2 with 0.5 equiv of MCl (M = Cu, Ag) or AuCl-tht (tht = tetrahydrothiophene). The molecular structures of these silylene complexes determined by XRD analysis and the DFT calculations suggested that the silylene–metal bond distances and bond angles around the two-coordinate metal center are dependent on the π acceptor ability and steric demands of the silylene ligands. Complexes 3Cu and 4Ag exhibit a fluxional behavior due to the chlorine migration between terminal silicon atoms in solution. The ease of 1,3-Cl migration increases in the order Au 3 4. The mechanisms of these migration reactions were investigated by DFT calculations.