Received 15 September 2012
In the asymmetric unit of the title compound, [Ag(C10H6N4)2(CF3CO2)], there two mononuclear but slightly different complex units. In each, two 2N:N-chelating 5-(pyridin-2-yl)pyrazine-2-carbonitrile ligands surround the AgI atom, giving an N4O square-pyramidal coordination geometry with one trifluoroacetate O atom at the apex. The difference between the two lies in the Ag-N bond lengths: in one complex, three normal [range 2.272 (5)-2.552 (5) Å] and one long [2.706 (4) Å] and in the second, two normal [2.254 (5) and 2.290 (5) Å] and two long [2.647 (5) and 2.675 (5) Å] are present. Short intermolecular FF contacts [2.586 (4) Å] and weak - stacking interactions [minimum ring centroid separation 3.836 (5) Å] between pyridyl and pyrazinyl rings connect the complex units, forming columns which extend along the b-axis direction.
For metal complexes with pyridyl-based ligands, see: Wang et al. (2009); O'Keeffe & Yaghi (2012); Choudhury et al. (2002). For complexes with 5-(pyridin-2-yl)pyrazine-2-carbonitrile, see: Wang et al. (2010); Zhang & Yang (2011). For van der Waals radii, see: Pauling (1960).
Data collection: APEX2 (Bruker 2007); cell refinement: APEX2 and SAINT (Bruker 2007); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009).
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: ZS2235 ).
The authors are grateful for financial support from the Science and Technology Program, Tianjin Municipal Commission.
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