Reactivity of 2,2′-Bis(2N-(1,1′,3,3′-tetramethyl-guanidino))diphenylene-amine with CuI and [Cu(MeCN)4][PF6]: Benzimidazole Formation vs. Cu Oxidation

The reaction of 2,2'-Bis(2N-(1,1',3,3'-tetramethyl-guanidino))diphenylene-amine (TMG(2)PA) (1) with CuI in MeCN results in the formation of [Cu-II(TMG(2)PA(amid))I] (2) indicating that Cu-I is the target of an oxidative attack of the N-H proton of the ligand which itself is converted to Molecular hydrogen. In contrast, if [Cu(MeCN)(4)][PF6] is used as the Cu-I Source, [Cu-2(I)(TMGbenz)(2)][PF6]2 (3) is obtained instead. The use of the non-coordinating counterion [PF6](-) apparently prevents Cu-I from oxidation but induces itself a cyclisation reaction within the ligand which results in the formation of a benzimidazole-guanidine ligand.