Poly[[(μ-2,2′-bipyrimidine-κ4 N 1,N 1′:N 3,N 3′)(μ-sulfato-κ2 O:O′)zinc(II)] monohydrate]

In the title compound, {[Zn(SO4)(C8H6N4)]·H2O}n, the ZnII atom is in a distorted octahedral environment. The ZnII atoms are bridged by both 2,2′-bipyrimidine and sulfate ligands, thus forming a three-dimensional polymeric metal–organic solid that contains uncoordinated water molecules in the interstitial space. O—H⋯O hydrogen bonding consolidates the crystal structure.

In the title compound, {[Zn(SO 4 )(C 8 H 6 N 4 )]ÁH 2 O} n , the Zn II atom is in a distorted octahedral environment. The Zn II atoms are bridged by both 2,2 0 -bipyrimidine and sulfate ligands, thus forming a three-dimensional polymeric metal-organic solid that contains uncoordinated water molecules in the interstitial space. O-HÁ Á ÁO hydrogen bonding consolidates the crystal structure.
Financial support from the National Science Foundation, awards CHE-0714555 and CHE-0714439, is gratefully acknowledged.

Comment
Metal-organic polymers utilizing the 2,2'-bipyrimidine (bpm) ligand are being studied due to the ability of bpm to produce interesting and potentially useful materials (Kawata et al., 1998;Marshall et al., 2000;Wang et al., 2007). Such features are often associated with the ability of this ligand to link metal centers through the bis-bidentate coordination mode (De Munno et al., 1995). Herein we report the crystal structure of the title compound, (I), that is a three-dimensional metal-organic framework where bpm binds Zn II atoms in this fashion.
The crystal structure of (I), which incidentally is isostructural with [Cu(bpm)(SO 4 )].H 2 O (Kawata et al., 1998), is a three-dimensional polymeric solid with an asymmetric unit consisting of one Zn II atom, two half-bpm ligands, a sulfate ligand, and one lattice water. The Zn II atom resides in a distorted octahedral environment composed of four N donors from a pair of equivalent bpm ligands, and two O atoms from two equivalent sulfate anions (Fig. 1). All of the Zn-N and Zn-O bond distances are in a normal range (Table 1).
The bpm ligand bridges Zn II atoms in a bis-bidentate fashion, producing undulating chains running along the [101] direction. Further, the sulfate ligand serves to bridge neighboring chains, thus forming a three-dimensional microporous solid. The pores are occupied by lattice waters that are hydrogen bonded to uncoordinated O2 and O3 atoms of nearby sulfate anions (Table 2 and Fig. 2).
It is also interesting to note that the crystal structure of (I) differs from that of [Zn 2 (µ-bpm)(H 2 O) 8 ](SO 4 ) 2 .2H 2 O (II) (De Munno & Julve, 1994), which contains the same chemical components as (I), but was synthesized under different synthetic conditions (see below).

Experimental
All starting chemicals were purchased from commercial sources and used as received. An aqueous solution of zinc sulfate heptahydrate (0.10 mmol, 10 ml) was slowly added to 10 ml of an ethanolic solution composed of bpm (0.050 mmol) and 4,4'-bipyridine (bpy) (0.050 mmol). Colorless, plate-like crystals formed within several weeks after slow evaporation of all the solvent under ambient conditions. Although bpy was not incorporated into the crystal structure of (I), it was required for synthesis of the crystalline product, as no such crystals were formed without it with all other conditions being the same. The synthesis in water alone using only zinc sulfate heptahydrate and bpm was reported to produce (II), as previously mentioned.