Synthesis, crystal structure, vibrational spectroscopy, optical properties and theoretical studies of a new organic–inorganic hybrid material: [((CH3)2NH2)+]6·[(BiBr6)3−]2

• Organic–inorganic based bismuth halides (III) have interesting optical properties.
• Their structures are characterized by MX6 octahedral sharing corners, edges or faces.
• Our hybrid material crystallizes in the triclinic P1¯ space group.
• The anionic sublattice composed of two (BiBr6)3− isolated octahedral.
• Absorption peaks are attributed to phenomena of charge transfer.

A new organic–inorganic hybrid material, [((CH3)2NH2)+]6·[(BiBr6)3−]2, has been synthesized and characterized by X-ray diffraction, FT-IR, Raman spectroscopy and UV–Visible absorption. The studied compound crystallizes in the triclinic system, space group P1¯ with the following parameters: a=8.4749(6)(Å)a=8.4749(6)(Å), b=17.1392(12)(Å)b=17.1392(12)(Å), c=17.1392(12)(Å)c=17.1392(12)(Å), α = 117.339(0)°, β = 99.487(0)°, γ = 99.487(0)° and Z = 2. The crystal lattice is composed of a two discrete (BiBr6)3− anions surrounded by six ((CH3)2NH2)+ cations. Complex hydrogen bonding interactions between (BiBr6)3− and organic cations from a three-dimensional network. Theoretical calculations were performed using density functional theory (DFT) for studying the molecular structure, vibrational spectra and optical properties of the investigated molecule in the ground state. The full geometry optimization of designed system is performed using DFT method at B3LYP/LanL2DZ level of theory using the Gaussian03. The optimized geometrical parameters obtained by DFT calculations are in good agreement with single crystal XRD data. The vibrational spectral data obtained from FT-IR and Raman spectra are assigned based on the results of the theoretical calculations. The energy and oscillator strength calculated by Time-Dependent Density Functional Theory (TD-DFT) results complements with the experimental findings. The simulated spectra satisfactorily coincide with the experimental UV–Visible spectrum. The results show good consistent with the experiment and confirm the contribution of metal orbital to the HOMO–LUMO boundary.

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