Rotational spectra of the diastereomers of Soman

The geometry of organophosphonates: Fourier-transform microwave spectroscopy and ab initio study of diethyl methylphosphonate, diethyl ethylphosphonate, and diisopropyl methylphosphonate

“…Despite the ambiguity, experimental data and ab initio calculations, combined with recent studies of dimethyl methylphosphonate (DMMP) [14][15][16] and the Gseries nerve agents sarin, soman, and cyclosarin [11][12][13] can be used to make general comparisons in organophosphonate structures between R-group size and the number of low-energy conformers that may be available, the number of low-energy conformers observed, and the relationship of the RAO groups to the internal rotation of the PACH 3 group in DMMP, DEMP, and DIMP, and the motion of the PACH 2 CH 3 group in DEEP.…”

“…6, another important axis of conformational motion is associated with rotation of the PAethyl group about the PAC bond (# 5 ), resulting in five separate torsional axes. Thus, the increase in the number of torsional axes is directly linked to the number of calculated low-energy conformers for DMMP, DEMP, and DEEP, being four [14], 6(7), and 15 (12), respectively, at the RHF (B3LYP) level of theory. Such conclusions are intuitive and not surprising.…”

“…Previous experimental work suggests that this interconversion barrier must be approximately 400 cm À1 [33] or more in order for a second conformer to be observed in the molecular beam. Such barriers exist in sarin [11] and soman [12], for example.…”

“…FTMW spectroscopy has routinely illustrated the ability to discriminate between multiple conq Supplementary data associated with this article can be found in the online version at doi: 10 formers and isotopomers of the same species [2][3][4]. Positive identification of several gas-phase analytes in a mixture has also been demonstrated [5].…”

“…A thorough comprehension of the low-potential energy surface of the molecule (roughly defined as the region 6 $400 cm À1 above the ground state) is important in understanding such mechanisms. Towards this end, previous work has been reported for the spectra of chemical warfare agents sarin [11], soman [12], cyclosarin [13], in addition to the simulant dimethyl methylphosphonate (DMMP) [14][15][16], and several ''mustard gas'' simulants (for example, ethyl sulfide [2], divinyl sulfide, divinyl sulfoxide, or divinyl sulfone [17]). …”