catena-[[(nitrato-κO)silver(I)]-μ-1,10-phenanthroline-5,6-dione-κ4 O,O′:N,N′]

In the title one-dimensional coordination polymer, [Ag(NO3)(C12H6N2O2)]n, the AgI atom is pentacoordinated by two N atoms from a 1,10-phenanthroline-5,6-dione (phen-dione) ligand, one O atom from the nitrate anion and two O atoms from another phen-dione ligand. The coordination environment around silver is slightly distorted square-pyramidal. Interestingly, the Ag—O distances to the phen-dione ligand are different [Ag—O = 2.612 (6) and 2.470 (5) Å]. The one-dimensional chains run parallel to [101] and are further interconnected by weak hydrogen bonds (C—H⋯O) and π–π stacking interactions [centroid–centroid distances 3.950 (4) and 3.792 (4) Å], forming a three-dimensional supramolecular network.

In this paper we report the synthesis and characterization of the title compound, [Ag(phen-dione)(NO 3 )] n (1). Singlecrystal X-ray diffraction study of 1 reveals the asymmetric unit to consist of one Ag (I) ion, one phen-dione ligand and one nitrate anion (Fig. 1). The silver atom is coordinated to two N atoms of a 1,10-phenanthroline-5,6-dione (phen-dione), one O atom from the nitrate anion and two O atoms from another phen-dione ligand giving rise to a slightly distorted square-pyramidal coordination sphere. The corresponding Ag-N bond distances are 2.445 (6) Å for Ag-N(1), 2.287 (6) (Young & Hanton, 2008;Wang et al., 2011;Sun et al., 2010).
In compound 1, the basic building units with a [AgN 2 O 3 ]center are firstly interconnected to each other to produce a one-dimensional chain by additional Ag-O(1 A) and Ag-O(2 A) bonds (Fig. 2). Then the adjacent one-dimensional chains are further linked to each other to form three-dimensional network structure by the weak hydrogen bond C (1)-H(1)···O (4) (3.184 Å) between a CH function of a pyridine and an oxygen atom of the nitrate anion and π-π stacking interactions (Fig.   3). Two types of aromatic stacking interactions in 1 are observed between pyridine ring I (N (1), C (10), C (9), C (8), C (7), C (11)) and pyridine ring II (N (1), C (10), C (9), C (8), C (7), C (11)). There is one close distance between the centroids of pyridine I and II and another between two neighboring pyridine I moieties. The respective centroid-to-centroid distances are 3.950 (4) Å and 3.792 (4) Å.
The combination of coordinative bonds, hydrogen bonds, and π-π stacking interactions assemble the one-dimensional chain into a complicated three-dimensional supramolecular network.

Experimental
The title compound was synthesized according to the following steps: a solution of silver (I) nitrate (0.068 g, 0.4 mmol) and phen-dione (0.0212 g, 0.1 mmol) in methanol (8 ml) was stirred for 2 h. After filtering, the filtrate was left at room temperature for about two weeks. Yellow block shaped crystals of 1 were collected by vacuum filtration, washed thoroughly with methanol dried in air (yield 23% based on silver).
supplementary materials sup-2 Refinement All non-hydrogen atoms were located from the difference Fourier maps, and were refined anisotropically. All H atoms were positioned geometrically, and were allowed to ride on their corresponding parent atoms with Uiso = 1.2 Ueq. Fig. 1. Molecular structure of the title compound, displacement ellipsoids are drawn at the30% probability level.

catena-[[(nitrato-κO)silver(I)]-µ-1,10-phenanthroline-5,6-dione-κ 4 O,O':N,N']
Crystal data [Ag(NO 3  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 > σ(F 2 ) is used only for calculating Rfactors(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.