Triangular Halogen Bond and Hydrogen Bond Supramolecular Complex Consisting of Carbon Tetrabromide,Halide, and Solvent Molecule： A Theoretical and Spectroscopic Study

The theoretical calculation and spectroscopic experiments indicate a kind of triangular three bonding supramolecular complexes CBr4…X^-…-H-C, which consist of carbon tetrabromide, halide, and protic solvent molecule （referring to dichloromethane, chloroform and acetonitrile）, can be formed in solution. The strength of halogen and hydrogen bonds in the triangular complexes using halide as common acceptor obeys the order of iodide〉bromide〉chloride. The halogen and hydrogen bonds work weak-cooperatively. Charge transfer bands of halogen bonding complexes between CBra and halide are observed in UV-Vis absorption spectroscopy in three solvents, and then the stoichiometry of 1：1, formation constants K and molar extinction coefficients ε of the halogen bonding complexes are obtained by Benesi-Hildebrand method. The K and ε show a dependence on the solvent dielectric constant and, on the whole, obey an order of iodide〉bromide〉chloride in the same solvents. Furthermore, the C-H vibrational frequencies of solvent molecules vary obviously with the addition of halide, which indicates the C-H…X- interaction. The experimental data indicate that the halogen bond and hydrogen bond coexist by sharing a common halide acceptor as predicted by calculation.

Triangular Halogen Bond and Hydrogen Bond Supramolecular Complex Consisting of Carbon Tetrabromide,Halide, and Solvent Molecule: A Theoretical and Spectroscopic Study

The theoretical calculation and spectroscopic experiments indicate a kind of triangu-lar three bonding supramolecular complexes CBr₄…X^-…H-C, which consist of carbon tetrabromide, halide, and protic solvent molecule (referring to dichloromethane, chloro-form and acetonitrile), can be formed in solution. The strength of halogen and hydro-gen bonds in the triangular complexes using halide as common acceptor obeys the order of iodide>bromide>chloride. The halogen and hydrogen bonds work weak-cooperatively. Charge transfer bands of halogen bonding complexes between CBr4 and halide are observed in UV-Vis absorption spectroscopy in three solvents, and then the stoichiometry of 1:1, for-mation constants K and molar extinction coefficients ? of the halogen bonding complexes are obtained by Benesi-Hildebrand method. The K and ? show a dependence on the solvent dielectric constant and, on the whole, obey an order of iodide>bromide>chloride in the samesolvents. Furthermore, the C-H vibrational frequencies of solvent molecules vary obviously with the addition of halide, which indicates the C-H…X^- interaction. The experimental data indicate that the halogen bond and hydrogen bond coexist by sharing a common halide acceptor as predicted by calculation.