Preparation of Au(I),Ag(I),and Pd(II) N-Heterocyclic Carbene Complexes Utilizing a Methylpyridyl-Substituted NHC Ligand.Formation of a Luminescent Coordination Polymer

摘要

Reaction of the imidazolium N-heterocyclic carbene precursor containing a methyl-substituted pyridyl functionality [HCH3im(CH3py)]PF6,1,with Ag20 produces the homoleptic Ag(I) complex,[Ag(CH3im(CH3py))2]PF6,2.In a simple carbene transfer reaction the analogous Au(I) species,[Au(CH3im(CH3py))2]PF6,3,is formed by treatment of 2 with Au(tht)Cl in dichloromethane.Both 2 and 3 are structurally similar with nearly linearly coordinated NHC ligands.The methyl group appended to the pyridyl ring inhibits rotation of the pyridyl group at room temperature.Addition of AgBF4 to a hot propionitrile solution of 3 followed by crystallization with diethyl ether yields the one-dimensional coordination polymer,{[AuAg(CH3im(CH3py))2(NCCH2CH3)](BF4)2}n,4,which contains Au-Ag separations of 2.9845-(5) and 2.9641(5) A with intermetallic angles of 167.642(14)° and 162.081(9)°.This material is intensely luminescent in the solid state and exhibits an emission band at 453 nm (lambda_(ex) = 350 nm).Nearly colorless [Pd(CH3im(CH3-py))2CI]PF6,5,is produced upon treatment of 2 with PdCl2(NCC6H5)2.The Pd(II) center in 5 is coordinated to one NHC ligand in a chelate fashion,while the second NHC is bound solely through the carbon center.The X-ray crystal structures of 1-5 are reported.