(Nitrato-κO)bis[5-(pyridin-2-yl)pyrazine-2-carbonitrile-κ2 N 4,N 5]silver(I)

In the mononuclear title complex, [Ag(NO3)(C10H6N4)2], two κ2 N:N′-chelating 5-(pyridin-2-yl)pyrazine-2-carbonitrile ligands surround the AgI atom, forming an N4O square-pyramidal coordination geometry with one nitrate anion bonding at the apical site. The two heterocyclic rings of the 5-(2-pyridin-2-yl)pyrazine-2-carbonitrile ligand are almost coplanar [dihedral angle = 5.63 (8)°], and the two chelating ligands are in an anti relationship. The mononuclear units are interconnected along [010] through C—H⋯O(nitrate) and C—H⋯N(cyano) interactions, forming an infinite chain. The mononuclear units are stacked along the a axis and interconnected via intermolecular π–π stacking interactions between adjacent pyridine and pyrazine rings [centroid–centroid distances = 3.984 (2) and 3.595 (3) Å], thus forming a three-dimensional supramolecular structure.


Experimental
The 5-(2-pyridyl)-2-cyanopyrazine ligand was obtained commercially. The ligand (18.1 mg, 0.1 mmol) and AgNO 3 (17 mg, 0.1mmol) were mixed and dissolved in 3 ml methanol, and then 1 ml acetonitrile was subsequently added to make the solution clear. After stirring at room temperature for 3 hours, the resulted solution was filtrated, and the clear solution was kept in air for about one week at room temperature to yield yellow block-like crystals (21.1.0 mg, 79% yield).

Refinement
All H atoms were discernible in the difference electron density maps. Nevertheless, they were placed into idealized positions and allowed to ride on the carrier atoms, with C-H = 0.93 Å and U iso (H) = 1.2U eq (C).
supplementary materials sup-2 Figures Fig. 1. The atom-numbering scheme of the title compound. Displacement ellipsoids are drawn at the 30% probability level.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.