Synthesis, structures and photoluminescence properties of silver complexes of cyclic (alkyl)(amino)carbenes

Silver complexes of cyclic (alkyl)(amino)carbenes (CAACs), (^RL)_nAgX (n = 1, X = Cl, Br, I; n = 2, X = OTf; R = Me₂, Et₂, or adamantyl) are accessible in high yields by reacting free carbenes with silver salts. The smaller carbene ligand ^Me2L leads to the formation of a mixture of neutral (^Me2L)AgCl and cationic [(^Me2L)₂Ag]⁺ products. The transmetallation of (^AdL)AgCl with copper and gold halides gives the corresponding copper and gold compounds (^AdL)MCl (M = Cu and Au) in a clean and quantitative reaction. Whereas (^Me2L)AgCl is monomeric in the solid state, (^Et2L)AgCl crystallizes as a Cl-bridged dimer. None of the compounds show metal-metal interactions. The complexes show blue photoluminescence, which consists of a fluorescence component with a lifetime of several nanoseconds, as well as a long-lived emission in the microsecond regime.