catena-Poly[[(4-aminobenzoato)aquasilver(I)]-μ-hexamethylenetetramine]

In the title coordination polymer, [Ag(C7H6NO2)(C6H12N4)(H2O)]n, the AgI ion is five-coordinated by two carboxylate O atoms from one 4-aminobenzoate anion (L), two N atoms from two different hexamethylenetetramine (hmt) ligands, and one water O atom in a distorted square-pyramidal geometry. The metal atom lies on a mirror plane and the L anion, hmt ligand and water molecule all lie across crystallographic mirror planes. Each hmt ligand bridges two neighboring AgI ions, resulting in the formation of a chain structure along the b axis. The chains are linked into a three-dimensional framework by N—H⋯O and O—H⋯O hydrogen bonds.

In the title coordination polymer, [Ag(C 7 H 6 NO 2 )(C 6 H 12 N 4 )-(H 2 O)] n , the Ag I ion is five-coordinated by two carboxylate O atoms from one 4-aminobenzoate anion (L), two N atoms from two different hexamethylenetetramine (hmt) ligands, and one water O atom in a distorted square-pyramidal geometry. The metal atom lies on a mirror plane and the L anion, hmt ligand and water molecule all lie across crystallographic mirror planes. Each hmt ligand bridges two neighboring Ag I ions, resulting in the formation of a chain structure along the b axis. The chains are linked into a threedimensional framework by N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds.

Experimental
An aqueous solution (10 ml) of HL (0.104 g, 0.5 mmol) was added to solid Ag 2 CO 3 (0.25 mmol) and stirred for several minutes until no further CO 2 was given off. A solution of hmt (0.5 mmol) in acetonitrile (10 ml) was then added and a white precipitate formed. The precipitate was dissolved by dropwise addition of an aqueous solution of NH 3 (14 M). Colourless blocks of the title compound were obtained by evaporation of the solution for several days at room temperature (33% yield).

Refinement
Amino and water H-atoms were located in a difference Fourier map, and refined freely. The remaining H atoms were positioned geometrically (C-H = 0.93 Å) and refined as riding, with U iso (H) = 1.2U eq (C). Fig. 1. A view of the local coordination of the Ag I centre in the title compound, showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 30% probability level. Symmetry codes: (i) x, 3/2 -y, z; (ii) x, 1/2 -y, z.

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 )
x y z U iso */U eq Occ. (