Anellated N-heterocyclic carbenes: 1,3-dineopentyl-benzimidazol-2-ylidene, structural aspects of C-protonated precursor salts and an AgCl complex

摘要

Access to 1,3-dineopentyl-benzimidazol-2-ylidene (1) by deprotonation of various benzimidazolium salts was studied. [Ag(1)Cl] was prepared from the corresponding benzimidazolium chloride. X-ray crystal structure analyses of benzo-, naphtho- and quinoxalino-anellated imidazolium salts displayed neither significant changes nor systematic trends of bond lengths and angles within the five-membered ring. Consistently downfield shifts of the (CH)-C-13-H-1(2) nuclei reflect the influence of electron-withdrawing anellation. (C) 2008 Elsevier Ltd. All rights reserved.