Electronic Properties and Crystal Packing Interactions in Bismuth(III) Iodide Thioamide Complexes: A Combined DFT and Hirshfeld Surface Study

A series of experimentally characterized complexes were selected from the literature to determine the electronic properties, energy levels, and to investigate the formation of the crystal lattice of bismuth(III) halide complexes. In this study, emphasis was placed on the parameters of EHOMO (Highest Occupied Molecular Orbital energy), ELUMO (Lowest Unoccupied Molecular Orbital energy), energy gap (∆E), chemical hardness (η), absolute electronegativity (χ), and electrophilicity (ω) for monomeric, dimeric, and polymeric bismuth(III) halide complexes. Comparison of the HOMO energy levels revealed that complex 1 possesses a higher electron-donating potential. The LUMO energy levels indicated that the monomeric unit of the polymeric structure (complex 3) is more prone to electron acceptance. Furthermore, according to the data obtained from Hirshfeld surface analysis, hydrogen bonding interactions were found to contribute most significantly to the formation of the crystal structures.