Sulfur and Selenium Ylide Bond Enthalpies

Abstract

The bond dissociation enthalpies (BDEs) of sulfur and selenium ylides have been estimated by applying MP2/6-311++G(3df,2p)//MP2/6-31G(d,p), G3, and other computational methods. Computed sulfoxide bond enthalpies were compared to experimental results to ensure the reliability of the computational methods before extending to related compounds. The examined ylides include the following: sulfoxides, sulfilimines, S,C-sulfonium ylides, and selenoxides. Selenoxides have BDEs about 10 kcal/mol smaller than the corresponding sulfoxides. N-H sulfilimines and CH2-S,C-sulfonium ylides have low BDEs, unless the sulfilimine or S,C-sulfonium ylide is stabilized by an electronegative substituent on N or C, respectively. Incorporation of the S or Se into a thiophene or selenophene-type ring lowers the BDE for the ylide. DisciplinesChemistry | Organic Chemistry | Other Chemistry | Polymer Chemistry CommentsReprinted (adapted) The bond dissociation enthalpies (BDEs) of sulfur and selenium ylides have been estimated by applying MP2/6-311++G(3df,2p)//MP2/6-31G(d,p), G3, and other computational methods. Computed sulfoxide bond enthalpies were compared to experimental results to ensure the reliability of the computational methods before extending to related compounds. The examined ylides include the following: sulfoxides, sulfilimines, S,C-sulfonium ylides, and selenoxides. Selenoxides have BDEs about 10 kcal/mol smaller than the corresponding sulfoxides. N-H sulfilimines and CH 2 -S,C-sulfonium ylides have low BDEs, unless the sulfilimine or S,C-sulfonium ylide is stabilized by an electronegative substituent on N or C, respectively. Incorporation of the S or Se into a thiophene or selenophene-type ring lowers the BDE for the ylide.

Photochemistry of thiophene‐S‐oxide derivatives

“…Geometries were optimized with the 6-31G(d) basis set, and the respective vibrational matrices showed that each structure was a minimum. It is well known that fairly large basis sets that contain tight d polarization functions are required to get good relative energies for the oxides of sulfur [13,[40][41][42][43][44][45][46][47][48][49][50][51][52] We thus used the aug-cc-pV(T þ d)Z basis set to obtain single point energies at the so-obtained geometries (i.e., MP2/aug-cc-pV(…”

“…[10] A much more modest degree of success was found with heavy atom substitution on the arene. [11] A much earlier hypothesis, though, was that derivatives of TO might be particularly good at deoxygenation because of their lower S-O bond dissociation enthalpies [12,13] and higher excited state energies (Table 1). (A potential flaw in this reasoning is the low triplet energy of cyclopentadiene, which might reasonably used as a first estimate for the triplet energy of TO.)…”

Modulation of Carbene Spin State Population through Precursor Photophysics

“…18 We believe this approach to carbene generation using one or more of the sulfonium ylides should be general for preparation of any carbene whose corresponding S,C ylide is synthetically accessible.…”

Effects of cross-linking methods for polyethylene-based carbon fibers: review

“…Such carbonization studies will be conducted in future investigations, as shown in Fig. 18a and b [96][97][98][99][100][101][102][103][104][105][106][107][108][109].…”