Chiral discrimination in hydrogen-bonded complexes of butan-2-ol and hydrogen peroxide

Abstract

We report a theoretical study on the chiral discrimination of different chiral formers of hydrogen-bonded complexes of butan-2-ol (“ga”, “ag”, and “gg”) with hydrogen peroxide. Complexes formed between two isolated chiral hydrogen peroxide (M and P) and chiral butan-2-ol (S) molecules have been investigated by second-order Møller–Plesset theory (MP2). Altogether, twelve minimum structures were located, and they are bound by intermolecular hydrogen bonds. Among the complexes, HOOH (M and P) and hydrogen atom of chiral carbon on the same side are named SM and SP, respectively; HOOH (M and P) and hydrogen atom of chiral carbon on the two sides are named SM-2 and SP-2, respectively. The largest chirodiastaltic energy of the two most stable complexes was found for SM–SP of “gg”, at −0.223 kcal mol −1 in favor of the SM complex in the “gg” configuration. The largest diastereofacial energy was found for (SM-2)-SM of “gg”, at 3.491 kcal mol −1 in favor of the SM complex in the “gg” configuration. Moreover, the diastereofacial interactions lead to a preference for the SM and SP over the SM-2 and SP-2 for all the butan-2-ol···HOOH complexes. The optimized structures, interaction energies and chirodiastaltic energies for various isomers were estimated. The harmonic frequencies, IR intensities, rotational constants and dipole moments were also reported.