Iodide Bismuth(III) Complexes with 1-Ethyl-3-methylpyridinium: Structure, Thermal Stability, and Optical Properties

Bismuth(III) halide complexes with 1-ethyl-3-methylpyridinium (1-Et-3-MePy) 3 [Bi 2 I 9 ] ( 1 ) and (1-Et-3-MePy) 3 [Bi 3 I 12 ] ( 2 ) have been synthesized when BiI 3 reacted with 1-ethyl-3-methylpyridinium iodide in organic solvents and characterized by X-ray diffraction analysis. The purity of samples has been confirmed by X-ray powder diffraction analysis. The diffuse reflectance spectra were recorded and the band gap was estimated using the classical Kubelka–Munk formula. The thermal stability has been studied by the TGA method. Based on the results of the data obtained, the following conclusions can be drawn: (i) the structure and composition of the product is affected not only by the ratio of reagents but also by the choice of solvent for the reaction; (ii) the resulting complex compounds have high thermal stability (mass loss begins only at >250°C); (iii) the band gap is 2.11 and 1.96 eV for compounds 1 and 2 , respectively.