Sulfur diimide

Sulfur diimides are chemical compounds of the formula S(NR)2. Structurally, they are the diimine of sulfur dioxide. The parent member, S(NH)2, is of only theoretical interest. Other derivatives where R is an organic group are stable and useful reagents.

Sulfur diimide
Names
IUPAC name
diimino-λ4-sulfane
Other names
2λ4-Diazathia-1,2-diene
Identifiers
3D model (JSmol)
ChemSpider
Properties
H2N2S
Molar mass 62.09 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references
Structure of S(NBu-t)2.

Organic derivatives

A particularly stable derivative is di-t-butyl‍sulfurdiimide.[1] It is prepared by reaction of tert-butylamine with sulfur dichloride to give the intermediate "S(N-t-Bu)", which decomposes at 60 °C to give the diimide. A second route to sulfur diimides involve treatment of sulfur tetrafluoride with amines. A third route involves transimidation of disulfonylsulfodiimide:

S(NSO2Ph)2 + 2 RNH2 → S(NR)2 + 2 PhSO2NH2

N,N'-Bis(methoxycarbonyl)sulfur diimide (MeO2C-N=S=N-CO2Me) is obtained from methyl carbamate.[2]

Structure, bonding, reactions

These compounds are related to SO2. They have planar C–N=S=N–C cores, with various combinations of E and Z isomers are observed for the two N=S bonds.[3]

Sulfur diimides are electrophilic. They undergo Diels–Alder reactions with dienes.[1] Organolithium reagents attack at the sulfur to give the corresponding nitrogen anion:

R'Li + S(NR)2 → R'S(NR)(NRLi)

The triimido analogues of sulfite can be generated by treating the sulfur diimides with a metal amide:[4]

4 LiNHBu-t + 2 S(NBu-t)2 → 2 Li2S(NBu-t)3 + 2 t-BuNH2

See also

References
  1. Kresze, G.; Wucherpfennig, W., "Organic synthesis with imides of sulfur dioxide", Angew. Chem. Int. Ed. Engl. 1967, volume 6, 149-167. doi:10.1002/anie.196701491
  2. Kresze, Günter; Braxmeier, Hans; Münsterer, Heribert (1987). "Allylcarbamates by the Aza-Ene Reaction: Methyl N-(2-Methyl-2-Butenyl)Carbamate". Organic Syntheses. 65: 159. doi:10.15227/orgsyn.065.0159.
  3. Lork, Enno; Mews, Ruëdiger; Shakirov, Makhmut M.; Watson, Paul G.; Zibarev, Andrey V. (2002). "The first N-alkyl-N′-polyfluorohetaryl sulfur diimide". Journal of Fluorine Chemistry. 115 (2): 165–168. doi:10.1016/S0022-1139(02)00047-7.
  4. Fleischer, R.; Stalke, D., "A new route to sulfur polyimido anions S(NR)nm-: reactivity and coordination behavior", Coord. Chem. Rev. 1998, 176, 431-450. doi:10.1016/S0010-8545(98)00130-1
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