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.