Halogen and hydrogen bonding to the Br atom in complexes of FBr

A computational study predicts a number of stable, unusual halogen- and hydrogen-bonded complexes involving FBr, NCH, and FH. Starting from the linear halogen-bonded FBr ⋯ NCH dimer, increasingly more stable complexes are obtained by the successive hydrogen bonding of one to three FH molecules to the lone pairs on the Br atom of FBr to form a trimer, tetramer, and pentamer. A hexamer is obtained from the pentamer by the bonding of FH to the F atom of FBr. The combined halogen and hydrogen bonding gives rise to a large computed zero-point corrected binding energy of 98 kJ/mol for the hexamer at the MP 2 / 6 - 31 + + G ( d , p ) level of theory.