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

Reaction of the imidazolium N-heterocyclic carbene precursor containing a methyl-substituted pyridyl functionality [HCH(3)im(CH(3)py)]PF6, with Ag2O produces the homoleptic Ag(I) complex, [Ag(CH(3)im(CH(3)py))(2)]PF6, . In a simple carbene transfer reaction the analogous Au(I) species, [Au(CH(3)im(CH(3)py))(2)]PF6, , is formed by treatment of with Au(tht)Cl in dichloromethane. Both 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 followed by crystallization with diethyl ether yields the one-dimensional coordination polymer, {[AuAg(CH(3)im(CH(3)py))(2)(NCCH2CH3)](BF4)(2)}(n), which contains Au-Ag separations of 2.9845(5) and 2.9641(5) A with intermetallic angles of 167.642(14)degrees and 162.081(9)degrees. This material is intensely luminescent in the solid state and exhibits an emission band at 453 nm (lambda(ex) = 350 nm). Nearly colorless [Pd(CH(3)im(CH(3)py))(2)Cl]PF6, is produced upon treatment of with PdCl2(NCC6H5)(2). The Pd(II) center in 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 are reported.