Synthesis, crystal structure and DFT calculations of a new Hg (II) metal-organic polymer

A new mercury (II) coordination polymer {2[Hg(L)I-2](HgI2)}(n) (1) [L: (E)-N'-(1-(pyridine-3-yl)ethylidene) isonicotinohydrazide] was synthesized by the reaction of mercury(II) iodide with the ligand under thermal gradient conditions using the branch-tube method and fully characterized by infrared spectroscopy, H-1 NMR, elemental analysis and single crystal X-ray diffraction. The determination of the structure by single crystal X-ray crystallography shows that the compound in the solid state consists of two distinct 1D polymeric chains, which will be denoted parts A and B. The coordination numbers of Hg (II) are four, (HgI4) of part A and (HgNI3) of part B with square planar and tetrahedral geometry around the mercury (II) ions. The supramolecular features in these complexes are guided and controlled by weak directional intermolecular interactions. The chains interact with each other through pi-pi and CH-pi stacking interactions creating a 3D framework. The structure of 1 was optimized by Density Functional Theory Calculations (DFT). Computed bond lengths and angles and vibrational frequencies are in good agreement with the experimental data.