Chiral discrimination in hydrogen-bonded complexes of 2-fluorooxirane with hydrogen peroxide

Abstract

The paper reports on an ab initio investigation of an extensive series of propylene oxide (PO)···hydrogen peroxide (HOOH) complexes to investigate chiral discrimination. Second-order Møller–Plesset perturbation theory (MP2) with the 6-311++G(d,p) basis set was used. Four complexes of 2–fluorooxirane (FO)···HOOH were identified and their structures as well as their calculated stability ordering were determined. Only–O–is the main interaction point and the–F is not a hydrogen bond acceptor in the four complexes. In this study, the four complexes were defined in a similar way as for PO···HOOH. The largest chirodiastaltic energy between RP-syn and RM-anti is 0.899 kcal mol−1 and the largest diastereofacial energy between RP-syn and RP-anti is 1.116 kcal mol−1. For the chiral 2,3-difluorooxirane (R,R), the chirodiastaltic energy is identical to the diastereomeric energy at 0.277 kcal mol−1. The results obtained were compared with previously reported results on propylene oxide(PO)···HOOH and 2-methylol oxirane(M-olOx)···HOOH complexes. The mechanisms of chiral discrimination in FO···HOOH, PO···HOOH and M-olOx···HOOH were discussed. The harmonic frequencies, IR intensities, rotational constants and dipole moments for the complexes were also presented to assist future spectroscopic investigation.