Investigation of dihydrogen bond interaction between cycloalkenes and alkali metal hydrides: a DFT approach

In this work, intermolecular dihydrogen bonded interactions between cycloalkenes (cyclobutene (C4H6), cyclopentene (C5H8), cyclohexene (C6H10)) and alkali metal hydrides H—M (M = Li, Na and K) complexes have been studied using B3LYP/6-311++G** method. The calculated structural parameters correlate well with the interaction energies and smallest dihydrogen bonded distance is observed for C4H6⋯HK complexes. Infrared vibrational frequency analysis indicates that significant red and blue shifts are occurring in the C—H and H—M bonds of all the complexes. The analyses of natural bond orbital, topological parameters based on the quantum theory of atoms in molecule and molecular electrostatic potential aids to know the nature of dihydrogen bonded interaction. The result shows that H⋯H interaction is strengthened in the C4H6⋯HK than the other complexes and henceforth H—K interacting complexes have better dihydrogen bonded interaction.