catena-Poly[[[aqua(pyridine-4-carboxylato-κN)silver(I)]-μ-hexamethylenetetraamine-κ2 N:N′] dihydrate]

In the title compound, {[Ag(C6H4NO2)(C6H12N4)(H2O)]·2H2O}n, the AgI atom shows a distorted triangular pyramidal geometry,, formed by two N atoms from two hexamethylenetetraamine (hmt) ligands and one N atom from a pyridine-4-carboxylate (4-pdc) ligand and one water molecule. The hmt ligands bridge the Ag atoms, forming a chain along [001]. The carboxylate group of the 4-pdc ligand is uncoordinated. O—H⋯O hydrogen bonds between the water molecules and carboxylate groups stabilize the structure.

In the title compound, {[Ag(C 6 H 4 NO 2 )(C 6 H 12 N 4 )(H 2 O)]Á-2H 2 O} n , the Ag I atom shows a distorted triangular pyramidal geometry,, formed by two N atoms from two hexamethylenetetraamine (hmt) ligands and one N atom from a pyridine-4carboxylate (4-pdc) ligand and one water molecule. The hmt ligands bridge the Ag atoms, forming a chain along [001]. The carboxylate group of the 4-pdc ligand is uncoordinated. O-HÁ Á ÁO hydrogen bonds between the water molecules and carboxylate groups stabilize the structure.

Related literature
For general background to the design and synthesis of coordination polymers, see: Eddaoudi et al. (2001).

Comment
The design and synthesis of coordination polymers have been a research field of rapid expansion not only because of their fascinating structures, but also owing to their interesting properties as new functional materials of tremendous potential applications in molecular recognition, ion-exchange, and catalysis for reactions (Eddaoudi et al., 2001). In this work, the reaction of pyridine-4-carboxylatic acid (4-Hpdc) and hexamethylenetetraamine (hmt) with Ag I ion yielded a new coordination polymer.
As shown in Fig. 1, the asymmetric unit of the title compound contains one Ag I atom, one 4-pdc ligand, one hmt ligand, one coordinated water molecule and two uncoordinated water molecules. The Ag1 atom shows a distorted triangle pyramidal geometry, completed by three N atoms from two hmt ligands and one 4-pdc ligand and one O atom from a water molecule.
The hmt ligands bridge the Ag atoms, forming a one-dimensional chain. The carboxylate group of the 4-pdc ligand is uncoordinated. O-H···O hydrogen bonds between the water molecules and carboxylate groups stabilize the structure.

Experimental
A mixture of 4-Hpdc (0.615 g, 0.5 mmol), Ag(NO 3 ) 2 (0.085 g, 0.5 mmol) and hmt (0.070 g, 0.5 mmol) in water was heated at 150°C in a Teflon-lined stainless steel autoclave for 5 d. The reaction system was then slowly cooled to room temperature.
Crystals suitable for X-ray diffraction analysis were collected by filtration.