trans-diaquabis{1,3-bis[5-(2-pyridyl)-2H-tetrazol-2-yl]propane}zinc(II) bis(perchlorate)

The Zn-II ion in the title compound, [Zn(C15H14N10)(H2O)(2)](ClO4)(2), lies on a centre of symmetry. The distorted N4O2 octahedral coordination environment around the Zn atom is composed of two 1,3-bis[5-(2-pyridyl)-2H-tetrazol-2-yl] propane ligands (L1) and two water molecules, coordinated in trans positions. The ligand acts as a typical bidentate chelating ligand through one of its 2-pyridyl-2H-tetrazole units, forming a five-membered Zn - N -C - C - N metallacycle with a small N - Zn - N bite angle [77.40 (8)degrees]. The other 2-pyridyl-2H-tetrazole unit remains uncoordinated. The average Zn - N distance (2.156 angstrom) is somewhat longer than the distance between the Zn-II center and the aqua ligand [2.108 (2) angstrom]. The coordinated pyridyl-tetrazoyl rings are quasi-coplanar, making a dihedral angle of 1.9 (2)degrees, while the uncoordinated rings show a larger interplanar angle of 21.3 (2)degrees. The flexible propane spacer displays a zigzag chain. Intermolecular O-H center dot center dot center dot N and O-H center dot center dot center dot O interactions result in two-dimensional polymeric structures parallel to (100). Two C atoms of the spacer are disordered over two positions, with site occupancy factors of ca 0.85 and 0.15.