NBO analysis of the structure of various alkyl-imidazolium derivatives with simple mono-atomic anions were studied at B3LYP level with DGDZVP basis set . However, there are no prior reported studies on the detailed NBO analysis of and those lying between these extremes are moderate hydrogen bonds. However, it is still the subject of scientific debate an ongoing research to establish a more robust level of knowledge relating to the E(2) n → σ* parameter with respect hydrogen bonds in ionic liquids. In particular, a large range of IL ion pair conformers need to be examined, geometric influences and the impact of multiple concomitant hydrogen bonds need be better understood. The NBO method has also been employed to characterize the natural orbital coefficients and hybrid orbital with 74.79% s character and 25.19% p characer) possesses a vintage overlap with the σ* C1-H1 orbital, while the interaction of the LP(2) orbital of O 1 with the σ* C1-H1 anti-bonding orbital is relatively larger. Furthermore, the percentage of "s" character of the lone pair orbital is another factor that determines the strength of H-bond interaction. The NBO analysis indicates that the "s" character of LP(1) of O 1 (74.79%) is greater than that of LP(2) orbital. While, the "p" character of LP(2) are higher than that of LP(1) on O 1 . Hence, the LP(1) should be more tightly held by the nucleus and reduced tendency for hyper conjugative charge transfer. Similarly, the π* N1-C1 NBO is formed from an sp 99.99 d 26.92 hybrid (99.69% p-character) on carbon interacting with an sp 1.00 hybrid orbital (99.93% p-character) on nitrogen corresponding to the linear combination of the orbitals 0.8461C(sp 99.99 d 26.92 ) ̶ 0.5330N(sp 1.00 ) comprising sp 1.00 hybrids (99.93% p-character) and larger polarization coefficient of C. The NBO analysis indicates that the "s" character of LP(1) (43.15%) is greater than that of the "s" character LP(2) of N 1 (0.00%) (see Table and "LP" for 1-center valence lone pair, "BD" for 2-center bond, "BD*" for 2-center antibond, and, the unstarred and starred labels corresponding to Lewis and non-Lewis NBOs, respectively), a serial number (1, 2,... if there is a single, double,... bond between the pair of atoms), and the atom(s) to which the NBO is affixed.