catena-Poly[[(benzoato-κ2 O,O′)(2,2′-bipyridine-κ2 N,N′)lead(II)]-μ3-nitrato-κ4 O:O,O′:O′′]

In the title coordination polymer, [Pb(C7H5O2)(NO3)(C10H8N2)]n, the PbII ion is eight-coordinated by two N atoms from one 2,2′-bipyridine ligand, two O atoms from one benzoate anion and four O atoms from three nitrate groups (one chelating, two bridging) in a distorted dodecahedral geometry. Adjacent PbII ions are linked by bridging nitrate O atoms through the central Pb2O2 and Pb2O4N2 cores, resulting in an infinite chain structure along the b axis. The crystal structure is stabilized by π–π stacking interactions between 2,2′-bipyridine and benzoate ligands belonging to neighboring chains, with shortest centroid–centroid distances of 3.685 (8) and 3.564 (8) Å.

In the title coordination polymer, [Pb(C 7 H 5 O 2 )(NO 3 )-(C 10 H 8 N 2 )] n , the Pb II ion is eight-coordinated by two N atoms from one 2,2 0 -bipyridine ligand, two O atoms from one benzoate anion and four O atoms from three nitrate groups (one chelating, two bridging) in a distorted dodecahedral geometry. Adjacent Pb II ions are linked by bridging nitrate O atoms through the central Pb 2 O 2 and Pb 2 O 4 N 2 cores, resulting in an infinite chain structure along the b axis. The crystal structure is stabilized bystacking interactions between 2,2 0 -bipyridine and benzoate ligands belonging to neighboring chains, with shortest centroid-centroid distances of 3.685 (8) and 3.564 (8) Å .

Comment
Complexes containing Pb(II) ion have recently attracted considerable interest not only because of the variety of their architectures, but also because of their potential applications, especially in environmental protection and in systems with different biological properties (Fan & Zhu, 2006;Hamilton et al., 2004;Alvarado et al., 2005). As an important family of multidentate O-donor ligands, aromatic carboxylate ligands have been extensively employed in the preparation of metal-organic complexes because of their potential properties and intriguing structural topologies (Wang et al., 2006;Masaoka et al., 2001). To our knowledge, carboxylate coordinates metal in various ways, for example, in the mode of monodentate, bidentate chelating, bidentate bridging or chelating-bridging. It is well known that the introduction of chelate ligands such as 2,2'-bipyridine are capable of passivating metal sites via the N donors of the organic groups and may induce new structural evolution (Hagrman et al., 2000;Li et al., 2002). Herein, we report the structure of the title polymer.
The asymmetric unit of the title compound, [Pb(C 10 H 8 N 2 )(C 7 H 5 O 2 )(NO 3 )], contains a Pb II cation, one 2,2'-bipyridine ligand, one benzoate and one nitrate ligand, as illustrated in in Fig.1. The Pb II atom is eight-coordinated by two N atoms from one 2,2'-bipyridine ligand, two O atoms from one benzoate anion and four O atoms from three chelating-bridging nitrate ligands in a distorted dodecahedron geometry. The O3 and O5 atoms of bridging nitrato ligands link the adjacent Pb II ions through the central Pb 2 O 2 and Pb 2 O 4 N 2 cores, resulting in an infinite chain structure along the b axis (Fig.2).
The excellent coordinating ability and large conjugated systems of 2,2'-bipyridine and benzoato ligands allow to form π..π interactions. The chains are extended into the framework through π..π stacking interactions between the ligands belonging to the neighboring chains, with the shortest centroid-centroid distance of 3.685 (8) and 3.564 (8)Å.

Refinement
All H atoms bounded to C atoms were placed in calculated positions and treated in a riding-model approximation, with C-H = 0.93 Å and U iso (H) = 1.2U eq (C). Fig. 1. The coordination environment around Pb II in the title compound with the atom-labeling scheme. Displacement ellipsoids for non-hydrogen atoms are drawn at the 30% probability level. Symmetry codes: (i) 1-x, -y, 1-z; (ii) -x, -y, 1-z.