Growth, optical, dielectric and ESR studies on tetrathiourea mercury(II) tetrathiocyanato manganate(II): An organometallic complex NLO crystal

Single crystals of tetrathiourea mercury(II) tetrathiocyanato manganate(II); Hg(N₂H₄CS)₄Mn(SCN)₄, (TMTM) were grown by slow solvent evaporation technique. The grown crystals were confirmed by single crystal and powder X-ray diffraction analysis. The optical absorption spectrum of TMTM in a mixed solvent of acetone and water shows the near ultra-violet cut-off wavelength corresponding to the absorption maximum as 335 nm. FT-IR spectrum identifies the characteristic absorption bands of thiourea and thiocyanate in both middle and far infrared regions, which further confirm the incorporation of both the ligands in the resulting compound. The electron spin resonance spectrum of TMTM was recorded both at room temperature and −196 °C, which reveals that the Mn environment is symmetrical with respect to the NCS ligand distribution. It is also interesting to note that there is no hyperfine coupling between Mn nucleus and its free electrons at both room temperature and −196 °C. The dielectric constant as well as dielectric loss of the sample were calculated for varying frequencies under different temperatures.