Carbene Wanzlick-Lappert-Arduengo

NHCs have novel chelating properties and have been shown to bind very strongly to a variety of metals to produce very stable complexes. In 1968 Ofele (J) and Wanzlick (2) used imid lium salt precursors to synthesize the fust transition metal N-heterocyclic carbene (NHC) con lexes of type 1. In 1982 Lappert synthesized several conq)lexes in which NHCs were bound to transition metals (i) and in 1991 Arduengo (4) reported the synthesis of a free isolable NHC. NHCs and their binding to transition metals are the subjects of several review articles (5, 6) and are of considerable interest in the field of catalysis. 

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