An Experimental Exploration of C-H⋅⋅⋅X Hydrogen Bond in [CHCl₃ -X(CH₃ )₂ ] Complexes (X=O, S, and Se)

Among the conglomeration of hydrogen bond donors, the C-H group is prevalent in chemistry and biology. In the present work, CHCl₃ has been selected as the hydrogen bond donor and are X(CH₃ )₂ are the hydrogen bond acceptors. Formation of C-H⋅⋅⋅X hydrogen bond under the matrix isolation condition is confirmed by the observation of red-shift in the C-H stretching frequency of CHCl₃ and comparison with the simulated spectra. Stabilisation energy of all the three complexes is almost equal although the observed red-shift for the C-H⋅⋅⋅O complex is less compared to the C-H⋅⋅⋅S/Se complexes. The nature and origin of the hydrogen bond have been delineated using Natural Bond Orbital, Atoms in Molecules, Non-Covalent Interaction analyses, and Energy Decomposition Analysis. Charge transfer is found to be proportional to the observed red-shift. This work provides the first impression of C-H⋅⋅⋅Se hydrogen bond and its comparison with C-H⋅⋅⋅O/S hydrogen bond interaction under experimental condition.