Crystal structure, DSC, IR and Raman studies in the compound NH3(CH2)5NH3HgCl4

The penthylene-diammonium tetrachloromercurate (II) salt is triclinic centrosymmetric with the following unit cell dimensions: a=7.7672(4)Angstrom, b=7.9754(6)Angstrom, c=10.9471(6)Angstrom, alpha=98.915(2)degrees, beta=109.363(2)degrees and gamma=91.463(2)degrees with Z=2. The structure consists of disordered penthylene-diammonium chains sandwiched between HgCl6 Octahedral layers. The chloromercurate sheet is packed as a result of hydrogen bonding to 1,5-penthylene diammonium ions. Ammonium groups at the ends of the chains fit into cavities of adjacent HgCl4 layers and form N-H...Cl hydrogen bonds. Thermal analysis indicates a hysteresis phenomenon characteristic of a first order phase transition. The Raman and IR spectra of polycrystalline samples of NH3(CH2)(5)NH3HgCl4 investigated at room temperature illustrate the conformational and statistical disorder of the organic chain. The system progressively gets ordered at low temperature, as the disorder of organic chains is due to a thermal effect.