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.