Experimental charge density study of 1,3-dithietane 1,1,3,3-tetraoxide (CH2SO2)2

Hypervalency in Organic Crystals: A Case Study of the Oxicam Sulfonamide Group

“…In particular, as the ellipticity approaches 0, there is a high level of sphericity, indicating a single or triple bond. In contrast, large deviations from 0 are indicative of double-bond structure and should be expected for the S–O bond structure proposed in the literature. − Surprisingly, the ellipticity across each S–O bond sits close to 0 for each S–O BCP, significantly less than what would be expected for a double bond (see E.S.I.6 Figure).…”

“…The sulfonamide group is one of the most widespread chemical groups found in pharmaceutical compounds, present in antibacterials, antiprotozoals, antifungals, nonsteroid anti-inflammatories (NSAID), nonpeptidic vasopressin receptor antagonists, and translation initiation inhibitors. − More recently, sulfonamide-containing compounds were shown to be useful as anticancer agents, antiviral HIV protease inhibitors, and in treating Alzheimer’s disease. − In accordance with valence bond theory (VBT), the S–O interaction of the sulfonamide group is often described as being a double bond, thus necessitating that the sulfur atom be hypervalent. , Within VBT, hypervalent atoms violate the octet rule through hybridization of the d n sp 3 orbitals, , but recent calculations have suggested that d-orbital contributions are artifacts of polarization functions in the selected basis set. − Most recently, the S–O bond in inorganic compounds was shown using Bader theory to be a highly polarized covalent bond without requiring that the S atom violate the octet rule . That said, many compounds that are not classified as being hypervalent under the VBT criteria may be deemed hypervalent within the definition proposed by Musher .…”

“…These calculations require careful parametrization of molecular parameters, and thus a thorough understanding of molecular structureparticularly for bonding groupsis needed. Previous works have suggested the S–O bond in similar molecules to be more complex than previously believed. , Thus, obtaining a complete understanding of the sulfonamide electronic structure in pharmaceutical molecules is crucial. This work employs a detailed topological analysis of the S–O bonding structure present in piroxicam [PXM; Figure ], through the framework of Bader’s quantum theory of atoms in molecules (QTAIM). − In recent years, a related topological tool, the source function (SF), was shown to give a feasible description of subtle electron-delocalization effects that determinate the molecular and crystal properties − and recently was also extended to plane waves (PW) to study periodic systems .…”

“…Previous works have suggested the S−O bond in similar molecules to be more complex than previously believed. 17,23 Thus, obtaining a complete understanding of the sulfonamide electronic structure in pharmaceutical molecules is crucial. This work employs a detailed topological analysis of the S−O bonding structure present in piroxicam [PXM; Figure 1], through the framework of Bader's quantum theory of atoms in molecules (QTAIM).…”

Bis(benzoxazol-2-yl)methanides in main group organometallic syntheses and enquiry-based education

“…[131] He claimed that atoms of heavier elements such as sulphur are not strictly bound by the octet rule due to involvement of d-orbitals in bond formation. [132] Although nowadays there is vast theoretical [133][134][135][136][137][138][139][140][141][142][143][144] as well as experimental [145] evidence suggesting the S-O bonds to be highly polarised covalent single bonds and not double bonds, depictions with hypervalent sulphur centres are still found in textbooks [146,147] and online resources. [148] Right: accurate depiction of the bonding situation according to the current state of knowledge.…”