catena-Poly[silver(I)-μ-acridine-9-carboxylato-κ3 N:O,O′]

In the title coordination polymer, [Ag(C14H8NO2)]n, the AgI cation is coordinated by two O atoms and one N atom from two symmetry-related acridine-9-carboxylate ligands in a distorted trigonal-planar geometry. The metal atoms are connected by the ligands to form chains running parallel to the b axis. π–π stacking interactions [centroid-to-centroid distances 3.757 (2)–3.820 (2) Å] and weak Ag⋯O interactions further link the chains to form a layer network parallel to the ab plane. The AgI cation is disordered over two positions, with refined site-occupancy factors of 0.73 (3):0.27 (3).

In the title coordination polymer, [Ag(C 14 H 8 NO 2 )] n , the Ag I cation is coordinated by two O atoms and one N atom from two symmetry-related acridine-9-carboxylate ligands in a distorted trigonal-planar geometry. The metal atoms are connected by the ligands to form chains running parallel to the b axis.stacking interactions [centroid-to-centroid distances 3.757 (2)-3.820 (2) Å ] and weak AgÁ Á ÁO interactions further link the chains to form a layer network parallel to the ab plane. The Ag I cation is disordered over two positions, with refined site-occupancy factors of 0.73 (3):0.27 (3).

Comment
In the synthesis of novel metal organic frameworks (MOFs), ligands play a key role in the construction of coordination polymers with fascinating topologies, intriguing architectures and useful physical-chemical properties. The acridine-9carboxylate anion is a potential bifunctional ligand with carboxylate and N-donor functional groups which has been used to prepare metal organic complexes possessing multidimensional networks and interesting properties Bu, Tong, Xie et al., 2005). Herein, we report the crystal structure of a novel polymeric silver(I) complex synthesized by the hydrothermal reaction of AgNO 3 with acridine-9-carboxylic acid in aqueous solution.
As shown in Fig. 1, the asymmetric unit of the title compound consists of a disordered silver(I) ion and one acridine-9-carboxylate anion. The cation is three-coordinated in a distorted trigonal planar geometry by two O atoms and one N atom from two symmetry-related acridine-9-carboxylate ligands. The Ag···O and Ag···N bond lengths range from 2.158 (4) to 2.499 (4) Å and bond angles vary from 55.02 (2) to 154.1 (2)°. The acridine-9-carboxylate ligands connect the metal centres to generate chains parallel to the b axis. The chains are further connected by π-π stacking interactions (the centroidto-centroid distances between neighbouring phenyl rings are 3.757 (2) and 3.820 (2) Å) and Ag···O weak interactions (2.844 (15)-3.348 (16) Å) to assemble a two-dimensional layer network parallel to the ab plane (Fig. 2).

Experimental
A mixture of AgNO 3 (0.170 g, 1 mmol), acridine-9-carboxylic acid (0.223 g, 1 mmol) and water (10 ml) was stirred vigorously for 60 min and then sealed in a Teflon-lined stainless-steel autoclave (20 ml capacity). The autoclave was heated and maintained at 423 K for 3 d, and then cooled to room temperature at 5 K h -1 and obtained the colourless block crystals.

Refinement
The disordered silver ion was refined over two sites, with refined occupancies of 0.73 (3) and 0.27 (3). H atoms attached to C atoms were placed at calculated positions and were treated as riding on their parent atoms with C-H = 0.93 Å, and with U iso (H) = 1.2U eq (C).

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.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )