Roles of Anion and Solvent in the Self-Assembly of Silver(I) Complexes Containing 2,3-Diphenylquinoxaline

Abstract

A series of Ag(I) complexes with zero-, one- and two-dimensional structures have been successfully prepared by the reactions of 2,3-diphenylquinoxaline, L, with corresponding Ag(I) salts in various solvents, which were characterized by elemental analysis, IR spectra and single crystal X-ray diffraction. Complexes of the type [Ag(L)2](X) (X = ClO4, 1; X = PF6, 2; and X = SbF6, 3) are monomeric, while the complexes {[Ag(L)(L′)][X]}∞ (X = BF4, L′ = H2O, 4; X = BF4, L′ = CH3CN, 5; and X = ClO4, L′ = CH3CN, 6), [Ag(L)(CF3SO3)·0.5CH3OH·H2O]∞, 7·0.5CH3OH·H2O, and {[Ag(L)][SbF6]·0.5CH2Cl2}∞, 8·0.5CH2Cl2, show 1-D polymeric infinite chains. The ClO4− anions in complex 6 interact with the rings in a tridentate bonding mode forming the rare [ClO4-π]n zigzag chain. The molecules of the complex Ag2(L)(NO3)2(DMF)2, 9, are dinuclear, while complexes of the type [Ag2(L)(NO3)2(L′)2]∞ (L′ = H2O, 10, and L′ = CH3CN, 11) show 1-D ladderlike chain structures, and the [Ag2(L)]2+ units are interlinked by H2O molecules and/or NO3− anions. The complexes [Ag2(L)(NO3)2]∞, 12, and [Ag(L)(p-TsO)]∞ (p-TsO = p-toluenesulfonate), 13, show 2-D distorted hexagonal net and 2-D pleated rectangular grids, respectively. For complexes 1−8 with noncoordinating anions, those with coordinated or packed solvent molecules show the polymeric structures, whereas those without solvent molecule are mononuclear. For complexes 9−13, the nitrate and p-toluenesulfonate ions are found to be coordinating and the bonding modes of nitrate anions are dependent on the nature of the solvents. All the complexes exhibit emissions which may be tentatively assigned as intraligand (IL) π → π* transitions.