A Viable Anionic N-Heterocyclic Dicarbene

The first anionic N-heterocyclic dicarbene, polymeric [:C{[N(2,6-(Pr2C6H3)-C-i)](2)CHCLi(THF)}](n) 1, containing both normal (C2) and abnormal carbene (C4) centers in the same five-membered imidazole ring (III), has been prepared by lithiation of the imidazole monocarbene, :C{N(2,6-(Pr2C6H3)-C-i)CH}(2). The dicarbene nature of 1 was unambiguously demonstrated by the formation of the group 13 Lewis acid adducts (THF)(2)Li:C{[N(2,6-Pe(2)(i)C(6)H(3))](2)CHC(LA)}, where LA = AlMe3 [2 center dot(THF)(2)] and BEt3 [3 center dot(THF)(2)].