(TeCl)4(TiCl4) with isolated Te4Cl16 and TiCl4 molecules and second-harmonic-generation

Abstract

(TeCl₄)₄(TiCl₄) is obtained by reaction of TeCl₄ and TiCl₄ at 50 °C with quantitative yield. The compound is composed of isolated, molecular (TeCl₄)₄ heterocubane-type units as well as isolated, molecular TiCl₄ tetrahedra. The (TeCl₄)₄ heterocubane is arranged like a body-centred cubic cell with TiCl₄ tetrahedra occupying 4 of 6 octahedral sites. (TeCl₄)₄(TiCl₄) crystallizes in the space group I with an unidirectional alignment of the tetrahedral building units. The structure of the compound is obtained from single crystal X-ray diffraction and confirmed by Rietveld refinement of powder diffraction data. Thermogravimetry, optical spectroscopy, infrared and Raman spectroscopy are employed to further characterize the title compound. Second harmonic generation (SHG) is observed with a strong intensity (1.6-times higher than potassium dihydrogen phosphate/KDP). The SHG effect is observed in the visible spectral regime as the band gap, derived from a Tauc plot, is 2.8 eV.