Where Are the Lone-Pair Electrons in Subvalent Fourth-Group Compounds?

Growth, crystal structure, Hirshfeld surface and vibrational properties of a new supramolecular hybrid material: (C4H7N2)2TeBr6

A novel tellurium (IV) hybrid compound with 2-methylimidazole was prepared. The crystal was grown by slow evaporation method from aqueous solutions at room temperature giving birth to a new compound with formula (C4H7N2)2TeBr6. The structure was determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic system, space group C 2/c, with the following parameters: a = 18.577(2)Å, b = 9.1497(10)Å, c = 13.5355(17)Å, α = 90°, β = 123.835(5)°, γ = 90° and Z = 8. The structure was solved with a final R = 0.044 for 2783 independent reflections. The crystal arrangement consists of [TeBr6]2− anions surrounded by [C4H7N2]2+ cations. The stability of the structure was ensured by hydrogen bonding contacts (N–H…Br) lengths that are in the range of 3.490–3.682 Å. The infrared spectra (FTIR) were recorded in the 4000–550 cm−1, confirming the existence of vibrational modes that correspond to the organic and inorganic groups. The crystal packing was stabilized mainly by Br…H (73.6%) interactions. Hirshfeld surface calculations were conducted to further investigate intermolecular interactions, associated 2D fingerprint plots and enrichment ratio, revealing the quantitatively relative contribution of these interactions in the crystal packing.