Abstract
The picoline‐functionalized benzimidazolium salts N‐alkyl‐N′‐picolylbenzimidazolium bromide [alkyl = methyl (1), ethyl (2), n‐propyl (3), n‐butyl (4)] and the dipicoline‐functionalized benzimidazolium bromide 5 have been synthesized. Reaction of the salts 1–4 with palladium acetate leads to the formation of the palladium complexes of the type [Pd(L)~2~]Br~2~ (6–9; L = N‐alkyl‐N′‐picolylbenzimidazolin‐2‐ylidene). Subsequent reaction of these complexes with AgBF~4~ gave the palladium complexes 10–13. The pincer‐type palladium complex [PdBrL]Br (14, L = N,N′‐dipicolylbenzimidazolin‐2‐ylidene) was prepared by deprotonation of the benzimidazolium salt 5 with n‐butyllithium and subsequent coordination of the unstable carbene intermediate to [PdBr~2~cod]. The molecular structures of the benzimidazolium salts 3 and 5 and the palladium complexes 7–9 and 11 have been determined by X‐ray diffraction. The bis(carbene) palladium complexes 6–9 as well as the monocarbene pincer‐type complex 14 have been used as precatalysts in Heck‐type coupling reactions of several aryl halides with styrene and n‐butyl acrylate as olefinic substrates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)