Transition metal precursor impact on thiocyanate complexes crystallization : Isomorphous cobalt and nickel properties

A novel hybrid organic-inorganic isomorphs, 2-Amino Piridinium di(isothiocyanate) cobalt (1) and 2-Amino Piridinium tetra(isothiocyanate)Nickel (2), were prepared by evaporation crystal growth method at room temperature and characterized by X-ray crystal structure, spectroscopic, electric and optical studies. The crystal structural analysis reveals that the solid (1) crystallizes in the monoclinic space group P 21/c and the solid (2) crystallizes in the triclinic space group P 1- . In (1) the metal cations are linked by pairs of μ-1,3-bridging thiocyanate anions into corrugated chains parallel to the b direction, whereas in (2) the [Ni(NCS)4]2− anions are arranged in pairs along the c-axis direction to form anionic layers parallel to the (a, c) plane. the crystal structure of (1) and (2) was determined from XRPD data, which shows that it is strongly related to the DRX mono-crystal obtained results. Intermolecular interactions were investigated by Hirshfeld surfaces and contact enrichment tools. Different interactions packed the system through N-H…N, and N-H…S hydrogen bonds forming a ring. The organic entities are grouped into dimers for (2) through weak interactions N-H…N and N-H…S. The robustness of the crystals is also enhanced by C–H…π of the piridinium ring and N–H…S intermolecular interactions. HOMO and LUMO energy gaps have been computed, where Gap energies revealed a semiconductor behavior. The vibrational absorption bands were identified by infrared spectroscopy. The solid-state UV-Visible absorption spectrum and the photoluminescence spectrum of the title compounds were obtained at room temperature in order to spotlight the optical properties. The di-electrical investigations on (1) and (2) shows an interesting electrical behavior. In the [20–400 °C] range, the thermal behaviors were investigated and showed the decomposition of the two complexes with metal complexes residues.