Synthesis of Pincer-Type Bis(benzimidazolin-2-ylidene) Palladium Complexes and Their Application in C−C Coupling Reactions

Reaction of the xylene-bridged bisbenzimidazolium salts 2,6-bis(N-alkyl-N‘-methylenebenzimidazolium)-1-bromophenylene dibromide (1, alkyl = ethyl; 2, alkyl = n-propyl; 3, alkyl = n-butyl) with [Pd2(dba)3]
yields the palladium pincer complexes of type [Pd(L)Br], 4−6 (L = 2,6-bis(N-alkyl-N‘-methylenebenzimidazolin-2-ylidene)phenylene). Pincer complexes 4−6 have been tested as precatalysts in Heck and
Suzuki coupling reactions of various aryl bromides with styrene and phenylboronic acid, respectively.