Related Experiment Video
Updated: Jul 11, 2026
10:42
Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of Chalcogenidoplumbates(II or IV)
Published on: December 29, 2016
Sulfur and selenium ylide bond enthalpies
Stacey A Stoffregen1, Ryan D McCulla, Robert Wilson
1Department of Chemistry, Iowa State University, Ames, Iowa 50011-3111, USA.
The Journal of Organic Chemistry
|October 2, 2007
Summary
Computational methods estimate bond dissociation enthalpies (BDEs) for sulfur and selenium ylides. Selenium ylides exhibit lower BDEs than sulfoxides, with stabilization effects noted for specific structures.
Area of Science:
- Computational chemistry
- Quantum chemistry
- Organosulfur and organoselenium chemistry
Background:
- Sulfur and selenium ylides are important chemical species with diverse applications.
- Understanding their stability is crucial for predicting reactivity and designing new molecules.
- Accurate estimation of bond dissociation enthalpies (BDEs) provides key insights into ylide stability.
Purpose of the Study:
- To computationally estimate the BDEs of various sulfur and selenium ylides.
- To compare the stability of selenium ylides with their sulfur counterparts.
- To investigate the influence of substituents and ring structures on ylide BDEs.
Main Methods:
- Application of advanced computational methods, including MP2 and G3 theories.
- Validation of computational results against experimental data for sulfoxides.
- Systematic examination of sulfoxides, sulfilimines, S,C-sulfonium ylides, and selenoxides.
Main Results:
- Selenium ylides generally possess BDEs approximately 10 kcal/mol lower than analogous sulfoxides.
- N-H sulfilimines and CH2-S,C-sulfonium ylides show reduced BDEs, particularly when lacking stabilizing electronegative substituents.
- Incorporation of sulfur or selenium into thiophene or selenophene rings decreases the ylide BDE.
Conclusions:
- Computational methods provide reliable estimations for ylide BDEs.
- Selenium ylides are intrinsically less stable than their sulfur analogs.
- Molecular structure, including substituents and cyclic incorporation, significantly modulates ylide stability.
Related Concept Videos
02:26Preparation and Reactions of Sulfides
Sulfides are the sulfur analog of ethers, just as thiols are the sulfur analog of alcohol. Like ethers, sulfides also consist of two hydrocarbon groups bonded to the central sulfur atom. Depending upon the type of groups present, sulfides can be symmetrical or asymmetrical. Symmetrical sulfides can be prepared via an SN2 reaction between 2 equivalents of an alkyl halide and one equivalent of sodium sulfide.
02:17Structure and Nomenclature of Thiols and Sulfides
Thiols and sulfides are sulfur analogs of alcohols and ethers, respectively, where the sulfur atom takes the place of the oxygen atom. Thus, thiols are generally represented as RSH, where R is an alkyl substituent and —SH is the functional group. On the other hand, in sulfides, the central sulfur atom is bonded to two hydrocarbon groups on either side. Depending upon the type of group, sulfides can be either symmetrical or asymmetrical. Both thiols and sulfides display a bent geometry, similar...
02:49Bond Energies and Bond Lengths
Stable molecules exist because covalent bonds hold the atoms together. The strength of a covalent bond is measured by the energy required to break it, that is, the energy necessary to separate the bonded atoms. Separating any pair of bonded atoms requires energy — the stronger a bond, the greater the energy required to break it.
02:33Preparation and Reactions of Thiols
Thiols are prepared using the hydrosulfide anion as a nucleophile in a nucleophilic substitution reaction with alkyl halides. For instance, bromobutane reacts with sodium hydrosulfide to give butanethiol.
02:45Valence Bond Theory
Overview of Valence Bond Theory
02:42Valence Bond Theory
Coordination compounds and complexes exhibit different colors, geometries, and magnetic behavior, depending on the metal atom/ion and ligands from which they are composed. In an attempt to explain the bonding and structure of coordination complexes, Linus Pauling proposed the valence bond theory, or VBT, using the concepts of hybridization and the overlapping of the atomic orbitals. According to VBT, the central metal atom or ion (Lewis acid) hybridizes to provide empty orbitals of suitable...