Hydrothermal synthesis and crystal structure of novel bis(6-carboxypyridine-2-carboxylato-κ3 O 2,N,O 6)nickel(II) trihydrate, Ni(Hpydc)2·3H2O

Abstract

The synthesis and crystal structure of the compound bis(6-carboxypyridine-2-carboxylato-κ3 O 2,N,O 6)nickel(II) trihydrate, Ni(Hpydc)2·3H2O, with a supramolecular network is reported (H2pydc is pyridine-2,6-dicarboxylic acid). The compound has been prepared by hydrothermal methods. The crystal structure has been solved by direct methods using single-crystal X-ray diffraction data collected at 293 K and refined by full-matrix least-squares procedures to a final R value of 0.0323 for 2779 observed reflections. The compound has distorted octahedral geometry around the metal centre. The complex contains two identical singly ionized ligand molecules. The nickel(II) is bonded to four O atoms and two N atoms from the tridentate ligand molecules, which are nearly perpendicular to each other. Hydrogen-bonded interactions create a three-dimensional supramolecular porous network. The supramolecular structure accounts for the porous structure of the compound as is evident from the Brunauer, Emmett & Teller (BET) surface area of 80 m2 g−1. Thermal degradation of the compound shows that lattice water molecules give stability to the crystal structure.