Stabile Carben-Addukte des Chlors / Stable Carbene Adducts of Chlorine

Abstract

The carbene adducts 3a-c (R 1 = Me, Et, iso-Pr; R2 = Me) are formed from the 2,3-dihydroimidazol-2-ylidenes la-c and 1,2-dichloroethane as air-sensitive solids in good yields. The compounds exhibit a reactive Cl-Cl bond. Benzene is chlorinated by 3a,b to give chlorobenzene and the imidazolium salts 10a,b under mild conditions. 3c acts as a chloride donor to give with AICI3 and S 0 2 the 2-chloroimidazolium salts 12c andl3c (X = A1C14, S 0 2C1). On hydrolysis, the less reactive hydrate salt 14c is formed from 3c. The X-ray structures of 10a and 14c are reported.

Imidazolium Dicyanoargentates

“…ylidene (1) is a high yield route to 2-chloro-1,3-diisopropyl-4,5-dimethylimidazolium chloride (2a) [6,7]. The imidazolium chloride (2a) reacts readily with silver cyanide in refluxing acetonitrile, and the imidazolium salt 3 is obtained as stable colorless crystals in high yield.…”

“…The nucleophilic attack of 2,3-dihydro-1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene (1) at hexachloroethane led to the formation of the chargetransfer adduct 2a in almost quantitative yield [6,7].…”

Heterocyclic Carbenes: Synthesis and Coordination Chemistry

“…The resonances for the carbene carbon atoms fall in the narrow range of d = 281.5-282.9 ppm in the 13 C NMR spectra of 63 a-c. The IR spectra of complexes [RhCl(CO) 2 (63)] were used to demonstrate that the s donor strength of the carbenes 63 a-c can be modulated by the exocyclic substituents at the boron atoms. The s-donor strength of the carbene ligand decreases together with the donor strength of the exocyclic substituents at the boron atoms in the order 63 a > 63 b > 63 c. [147] The anionic carbene 64 was isolated and characterized as the lithium adduct.…”

Synthesis and properties of heteroaromatic carbenes of the imidazole and triazole series and their fused analogues

“…383 Chlorination of imidazol-2-ylidenes was carried out using dichloroethane, and the resulting products were identified L Cl2 although the exact structures were not determined. 384 However, the complexes did exhibit chlorinating action, indicative of their containing a reactive Cl-Cl bond. Similar chlorinated complexes from the reaction of 4,5-dichloroimidazol-2-ylidenes and CCl4 were determined to be the 2,4,5-trichloroimidazolium salts.…”

“…9 Reactions with halogens form either halogenazolium salts or carbene complexes with halogens. 383,384 The structure of a reaction product with iodine proved to be a carbene complex with an extended I-I bond. 383 Chlorination of imidazol-2-ylidenes was carried out using dichloroethane, and the resulting products were identified L Cl2 although the exact structures were not determined.…”