title: 2-chloro-azaborolyl anion: a source of 1,2-azaborole isosteric to cyclopentadienylidene.
abstract: Azaborolyl anions, the five-membered BN heterocycles, have attracted a considerable attention due to their aromaticity and isoelectronic relationship with ubiquitous cyclopentadienyl ligands. Besides their syntheses and applications in the preparation of metal complexes, the other aspects of their chemistry have been virtually unexplored. Reduction of the azabutadienyl chelate boron dichloride [ArNC(R)CHC(R)]BCl2 (2, Ar=2,6-Me2 C6 H3 , R=tBu) with two equivalents of potassium yielded the novel 2-chloro-azaborolyl anion [ArNC(R)CHC(R)BCl]K(thf) (3) as a stable product in good yield. Reaction of 3 with 1,3,4,5-tetramethylimidazol-2-ylidene (NHC) yielded the first NHC-azaborole adduct with the elimination of KCl. The salt elimination reaction was also observed in the reactions with H2 O and the organic azide ArN3 , leading to the formation of an oxo-bridged 3H-1,2-diazaborole and an intramolecular donor-stabilized iminoborane, demonstrating that 3 is a source of the unexplored 1,2-azaborole isosteric to cyclopentadienylidene.
authors: State Key Laboratory of Elemento-Organic Chemistry, Nankai University; Collaborative Innovation Center of Chemical Science and Technology (Tianjin), Tianjin, 300071 (P.R. China), Fax: (+86) 22-23503461.
authors: Liang
authors: L
authors: Xie
authors: Jianying
authors: J
authors: Zhang
authors: Chunming
authors: C
authors: Cui
keywords: BN heterocycle; KCl elimination; azaborolyl anion; diradical; potassium reduction