Synthesis, characterization, crystal structures and thermal and fluorescence studies of dinuclear and polymeric silver(I) complexes of 5,5-diethylbarbiturate with 2,5-dimethylpyrazine and piperazine involving Ag-Ag interactions

Abstract

Two silver(I) complexes, [Ag(dmpyz)(2)][Ag(barb)(2)] (1) and {[Ag(ppz)][Ag(barb)(2)]center dot H2O} (n) (2) (barb = 5,5-diethylbarbiturate, dmpyz = 2,5-dimethylpyrazine and ppz = piperazine), have been synthesized and characterized by elemental analyses, IR, thermal analysis (TG-DTA) and single-crystal X-ray diffraction. Complex 1 consists of [Ag(dmpyz)(2)](+) and [Ag(barb)(2)](-) ions in which the silver(I) ions are linearly coordinated by two dmpyz or two barb ligands. These two ions are connected by strong Ag-Ag interactions (Ag-Ag = 2.896 (1) ). Complex 2 is a 1D coordination polymer in which the silver(I) ions are bridged by the ppz ligands in a linear fashion, leading to a zigzag chain of [Ag(ppz)] (n) (+) , which interacts with the [Ag(barb)(2)](-) units by Ag-Ag interactions of 3.183 (1) . The 1D chains are further assembled to form 3D networks by strong N-H center dot center dot center dot O and OW-H center dot center dot center dot O hydrogen bonds. IR spectra and TG-DTA data are in agreement with the crystal structures. The fluorescent properties of 1 were also evaluated.