CRYSTAL-STRUCTURES OF 2-PYRAZINECARBOXYLATO SILVER(I) AND AMMINE 2,3-PYRAZINECARBOXYLATO DISILVER(I)

X-ray analysis has shown that the complexes of silver(I) with the anio nic forms of 2-pyrazinecarboxylic and 2,3-pyrazinedicarboxylic acids a re three-dimensional network polymers. Ag(C5H3O2N2) (I) crystallizes i n space group Pna2(1) with a = 7.028(2), b = 11.510(3), c = 6.949(2) a ngstrom and Z = 4. Silver tetrahedral coordination occurs through thre e ligands: the first one acts as a bidentate chelator (Ag - O = 2.539( 4), Ag-N = 2.334(4) angstrom), the second one involves one N pyrazine atom (Ag-N = 2.196(4) angstrom) and the third one bonds through one O- carboxylato atom (Ag-O = 2.323(4) angstrom). The dinuclear complex Ag2 (C6H2O4N2)(NH3) (2) crystallizes in space group P2(1)/c with a = 7.775 (2), b = 16.455(2), c = 7.174(1) angstrom, beta = 115.21(1)-degrees an d Z = 4. Each of the two silver atoms shows a trigonal environment. Th e first silver atom involves two O carboxylic atoms (Ag-O = 2.312(4), 2.374(4) angstrom) and one N pyrazine atom (Ag - N = 2.277(3) angstrom ) belonging to three different ligands. The second one involves one O carboxylic atom (Ag-O = 2.364(3) angstrom) and one N pyrazine atom (Ag -N = 2.304(4) angstrom) from the same chelating ligand and one N ammin e atom (Ag-N = 2.158(5) angstrom).