Synthesis, structural characterization and spectroscopic studies of bis tetramethylammonium hexabromostannate [N(CH3)4]2SnBr6

• Published in: Journal of alloys and compounds Vol. 772; pp. 546 - 556
• Main Authors: Mhiri, Akram, Krichen, Firas, Oueslati, Abderrazek, Lhoste, Jerome, Goutenoire, François, Gargouri, Mohamed, Bulou, Alain
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 25-01-2019; Elsevier
• Subjects: Chemical synthesis; Condensed Matter; Crystal structure; DFT; EDS analysis; Hartree-Fock; Materials Science; Physics; PXRD; Raman and IR spectroscopy; Hartree-Fock; DFT; EDS analysis; Raman and IR spectroscopy; Chemical synthesis; Crystal structure; PXRD
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2018.09.158

The compound [TMA]2SnBr6 (TMA = Tetramethylammonium = N(CH3)4) has been synthesized by slow evaporation and its crystal structure was determined by single crystal X-ray diffraction. The [TMA]2SnBr6 crystallizes in the cubic system (Fm3¯m space group) with cell parameter a = 13.2554(15) Å. It can be considered as derived from a perovskite structure in which half of the octahedral symmetry sites are occupied by [SnBr6]2- octahedra and half by vacancies. The purity of the compound was checked by EDS measurement and Rietveld refinements.
The Raman and infrared spectra at room temperature are recorded in the wavenumber range 10–3600 cm−1 and 400-4000 cm−1, respectively. Ab-initio calculations have been performed using the Gaussian 98 program at room temperature. Hartree-Fock (HF) and B3LYP density functional theory (DFT) methods with 6-31G (d) and LanL2DZ basis sets were used to obtain equilibrium geometry and the fundamental vibrational frequencies and spectroscopic intensities of the free polyhedra [(N(CH3)4]+ and [SnBr6]2-. The overall results are consistent with the experimental ones and group theory analysis, but also clearly show extra features that suggest disorder of the methyl groups of TMA.
•A new hybrid perovskite compound, [TMA]2SnBr6 was synthesized by slow evaporation.•A cubic Fm3¯m crystal structure was determined by XRD at room temperature.•The intermolecular interactions were analyzed by Hirshfeld Surfaces.•IR and Raman spectra are consistent with the structure and ab initio calculations.