Shedding light on the strength, nature, and cooperativity/anti-cooperativity between intermolecular H…N hydrogen and Cl…C halogen bonds in the competitive binary and ternary complexes

Abstract

In equimolar mixture of monomers N≡C-Cl (M−1) and C=N-H (M−2), formation of N…H hydrogen-bonded complex HB-Dim and C…Cl halogen-bonded complex XB-Dim compete with each other. Values of counterpoise-corrected interaction energy indicate that HB-Dim is absolute winner in such a competition. Existence of N…H HB- and C…Cl XB-interactions is characterized through geometrical parameters analysis, Quantum theory of atoms-in-molecules descriptors, and Independent gradient model based on Hirshfeld partition of molecular density. Interaction energy decomposition reveals that electrostatic with orbital interactions and, electrostatic with dispersion interactions are main driving forces for the formation of, respectively, HB- and XB-Dim. Moreover, substantially stronger electrostatic and orbital interactions characterized with Molecular electrostatic potential and Extended Transition State-Natural Orbitals for Chemical Valence analyses explain why formation of HB-Dim is quite preferred over that of XB-Dim. Two N…H HB- and C…Cl XB-interactions, present at the same time, make each other slightly strength in ternary complex Trim.