Chemistry:Sulfilimine
In chemistry, a sulfilimine (or sulfimide) is a type of chemical compound containing a sulfur-to-nitrogen bond which is often represented as a double bond (S=N). In fact, a double bond violates the octet rule, and the bond may be considered a single bond with a formal charge of +1 on the sulfur and a formal charge of −1 on the nitrogen. The parent compound is sulfilimine H
2S=NH, which is mainly of theoretical interest.
Examples include S,S-diphenylsulfilimine[1] and sulfoximines [Category] such as methylphenylsulfoximine:[2]
In the case of a sulfoximine, the bonds can be considered single bonds, with formal charges of −1 on both the oxygen and the nitrogen, and a formal charge of +2 on the sulfur.
Preparation
Most sulfilimines are N-substituted with electron-withdrawing groups. These compounds are typically prepared by oxidation of thioethers with electrophilic amine reagents, such as chloramine-T in the presence of a base:[3]
- R
2S + ClNHTs → R
2S=NTs + HCl
An alternative route involves reactions of electrophilic sulfur compounds with amines. The imidosulfonium reagents provide a source of "Me
2S2+", which are attacked by amines.
In general, aliphatic sulfilimines, unsubstituted at N, are not stable above −30 °C (−22 °F).[4]
KMnO4 can oxidize sulfilimines to sulfoximines, but the latter are more generally produced from addition of azides to sulfoxides.[4]
Sulfilimine bonds in proteins
Sulfilimine bonds stabilize collagen IV strands found in the extracellular matrix,[5] and evolved at least 500 mya.[6] These bonds covalently connect hydroxylysine and methionine residues of adjacent polypeptide strands to form a larger collagen trimer.
References
- ↑ "S,S-Diphenylsulfilimine". Sigma-Aldrich. https://www.sigmaaldrich.com/catalog/product/aldrich/232173.
- ↑ "(R)-(−)-S-Methyl-S-phenylsulfoximine". Sigma-Aldrich. https://www.sigmaaldrich.com/catalog/product/aldrich/68916.
- ↑ Gilchrist, Thomas L.; Moody, Christopher J. (1977). "The chemistry of sulfilimines". Chemical Reviews 77 (3): 409–435. doi:10.1021/cr60307a005.
- ↑ 4.0 4.1 Roesky, H. W. (1971). "The Sulfur–Nitrogen Bond". in Senning, Alexander. Sulfur in Organic and Inorganic Chemistry. 1. New York: Marcel Dekker. pp. 27-28,30-31. ISBN 0-8247-1615-9.
- ↑ "A sulfilimine bond identified in collagen IV.". Science 325 (5945): 1230–1234. September 4, 2009. doi:10.1126/science.1176811. PMID 19729652. Bibcode: 2009Sci...325.1230V.
- ↑ Fidler, Aaron L.; Vanacore, Roberto M.; Chetyrkin, Sergei V.; Pedchenko, Vadim K.; Bhave, Gautam; Yin, Viravuth P.; Stothers, Cody L.; Rose, Kristie Lindsey et al. (2014). "A unique covalent bond in basement membrane is a primordial innovation for tissue evolution". Proceedings of the National Academy of Sciences 111 (1): 331–336. doi:10.1073/pnas.1318499111. PMID 24344311. Bibcode: 2014PNAS..111..331F.
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