Complexes of Diiodine with Heteroaromatic -Oxides: Effects of Halogen-Bond Acceptors in Halogen Bonding.

Halogen bonding (XB) in complexes of diiodine with heteroaromatic -oxides was examined via a combination of UV-vis spectral and X-ray structural measurements, as well as computational analysis. While all of these associates were formed by analogous I···O bonds, they showed considerable variations of formation constants (5-1500 M) and intermolecular I···O bond length (2.3-3.

Resolving the halogen vs. hydrogen bonding dichotomy in solutions: intermolecular complexes of trihalomethanes with halide and pseudohalide anions.

Halogen- and hydrogen-bonded complexes between trihalomethanes, CHX3, and (pseudo-)halide anions, A-, co-existing in acetonitrile solutions were identified and characterized via a combination of UV-vis and NMR spectral measurements with the results of X-ray structural and computational analyses. Halogen-bonded [CHX3, A-] complexes displayed strong absorption bands in the UV range (showing Mulliken correlations with the frontier orbital energies of the interacting species) and a decreased shift of the NMR signal of trihalomethanes' protons. Hydrogen bonding led to the opposite (increased) NMR signal shift and the UV-vis absorption bands of the hydrogen-bonded [CHX3, A-] complexes were similar in intensity to those of the separate CHX3 molecules.