Bis(pyridine-3-carboxylic acid-κN)silver(I) perchlorate

In the title compound, [Ag(C6H5NO2)2]ClO4, the AgI atom shows an almost linear coordination geometry, defined by two N atoms from two pyridine-3-carboxylic acid ligands. The complex cations are linked by hydrogen bonds between the carboxyl groups into a chain. The chains are further connected through C—H⋯O hydrogen bonds and a weak Ag⋯O interaction [2.757 (8) Å] into a layer. Another Ag⋯O interaction [2.899 (2) Å] and a C—H⋯O hydrogen bond connect the layers into a three-dimensional network.

In the title compound, [Ag(C 6 H 5 NO 2 ) 2 ]ClO 4 , the Ag I atom shows an almost linear coordination geometry, defined by two N atoms from two pyridine-3-carboxylic acid ligands. The complex cations are linked by hydrogen bonds between the carboxyl groups into a chain. The chains are further connected through C-HÁ Á ÁO hydrogen bonds and a weak AgÁ Á ÁO interaction [2.757 (8) Å ] into a layer. Another AgÁ Á ÁO interaction [2.899 (2) Å ] and a C-HÁ Á ÁO hydrogen bond connect the layers into a three-dimensional network.
Data collection: APEX2 (Bruker, 2007); cell refinement: 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. supporting information Acta Cryst. (2009). E65, m148 [doi:10.1107/S1600536808044206] Bis(pyridine-3-carboxylic acid-κN)silver(I) perchlorate Xiao-Yan Nie and Qian-Zhu Li S1. Comment The use of multifunctional organic linker molecules in the preparation of coordination polymers and open-framework materials has led to the development of a rich field of chemistry owing to the potential applications of these materials in catalysis, separation, gas storage and molecular recognition (James, 2003;Serre et al., 2004;Yaghi et al., 1998Yaghi et al., , 2003. In our investigations we used nicotinic acid ligands for the preparation of new coordination polymers, because it can act as a multidentate ligand with versatile binding and coordination modes (Evans & Lin, 2001;Luo et al., 2004). In this paper, we report the crystal structure of the title compound, a new Ag I complex obtained by the reaction of nicotinic acid, AgNO 3 and perchloric acid in water.
As shown in Fig. 1, the title compound consists of a [Ag(C 6 H 5 NO 2 ) 2 ] + cation and a perchlorate anion. The Ag I atom exhibits a linear coordination geometry, defined by two N atoms from two pyridine-3-carboxylic acid ligands (Table 1).

S2. Experimental
A mixture of AgNO 3 (0.169 g, 1 mmol), perchloric acid (0.12 ml), nicotinic acid (0.123 g, 1 mmol) and H 2 O (10 ml) was placed in a 23 ml Teflon-lined reactor, which was heated to 433 K for 3 d and then cooled to room temperature at a rate of 10 K h -1 . The crystals obtained were washed with water and dried in air.

S3. Refinement
H atoms on C atoms were positioned geometrically and refined as riding atoms, with C-H = 0.93 Å and U iso (H) = 1.2U eq (C). H atoms on O atoms were located in difference Fourier maps and were fixed with O-H = 0.82 Å and U iso (H) = 1.5U eq (O). The highest residual electron density was found 1.31 Å from atom O7 and the deepest hole 0.46 Å from atom O7.  The structure of the title compound. Displacement ellipsoids are drawn at the 30% probability level.