Short metal-metal separations in a highly luminescent trimetallic Ag(I) complex stabilized by bridging NHC ligands

Reaction of 1,3-bis(2-pyridinylmethyl)-1H-imidazolium salt, [H(pyCH(2))(2)im]X (X = BF4- or Cl-), with silver oxide in acetonitrile readily yields yellow-brown [((pyCH(2))(2)iM)(2)Ag]X, 1.BF4 or 1.Cl. The chloride salt crystallizes with 3.650 Angstrom intermolecular Ag...Ag interactions while 1.BF4 shows no short intermolecular interaction. Addition of excess Ag(BF4) produces the homoleptic carbene bridged trimetallic species, [(mu-NHC)(3)Ag-3](BF4)(3), 2. This species contains very short Ag-Ag separations between 2.7249(10) and 2.7718(9) Angstrom. In solution, these complexes are photoluminescent.