Studies of the reactivity of N-heterocyclic carbenes with halogen and halide sources
作者:Marcus L. Cole、Cameron Jones、Peter C. Junk
DOI:10.1039/b204422f
日期:2002.9.23
The reactivity of the N-heterocyclic carbene (NHC) 1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene, IMes, with a series of halide sources, including 1,1,1,2,2,2-hexachloroethane, 1,2-dibromoethane and dibromine, has been assessed. These result in the formation of the imidazolium species 1,3-bis(2,4,6-trimethylphenyl)-2-chloroimidazolium chloride, [IMesCl][Cl], 1,3-bis(2,4,6-trimethylphenyl)imidazolium bromide, [IMesH][Br] and 1,3-bis(2,4,6-trimethylphenyl)-2-bromoimidazolium bromide, [IMesBr][Br]. Treatment of IMes with 2.0 equiv. of carbon tetrabromide, CBr4, in tetrahydrofuran or benzene yields the new NHC 1,3-bis(2,4,6-trimethylphenyl)-4,5-dibromoimidazol-2-ylidene, IMesBr2. IMesBr2 is indefinitely stable in air and has been characterised by XRD. The molecular and supramolecular structures of compounds [IMesBr][Br]·3MeCN, [IMesH][Br], [IMesCl][Cl]·MeCN and [IMesCl][AlCl4], the latter formed from the addition of aluminium trichloride to [IMesCl][Cl], are discussed.
我们评估了 N-杂环碳烯(NHC)1,3-双(2,4,6-三甲基苯基)
咪唑-2-亚基(IMes)与一系列卤化物源(包括 1,1,1,2,2,2-
六氯乙烷、
1,2-二溴乙烷和二
溴)的反应性。这些物质会形成
咪唑鎓物种 1,3-双(2,4,6-三甲基苯基)-
2-氯咪唑鎓
氯化物 [IMesCl][Cl]、1,3-双(2,4,6-三甲基苯基)
咪唑鎓
溴化物 [IMesH][Br] 和 1,3-双(2,4,6-三甲基苯基)-2-
溴咪唑鎓
溴化物 [IMesBr][Br]。在
四氢呋喃或苯中用 2.0 等量的
四溴化碳 CBr4 处理 IMes,可得到新的 NHC 1,3-双(2,4,6-三甲基苯基)-4,5-二
溴咪唑-2-亚基,即 IMesBr2。IMesBr2 在空气中无限稳定,并通过 XRD 进行了表征。本文讨论了[IMesBr][Br]-3MeCN、[IMesH][Br]、[IMesCl][Cl]-MeCN 和[IMesCl][AlCl4]化合物的分子结构和超分子结构。