Protic and substituted NCN palladium(II) pincer complexes with 1,3-bis(benzimidazol-2 ′-yl)-2-bromobenzenes: Structure and catalysis

Publication date: Available online 2 February 2018 Source:Journal of Organometallic Chemistry Author(s): Varsha Rani, Harkesh B. Singh, Ray J. Butcher A new class of sparingly soluble NCN palladium(II) pincer complexes of the type (N ˆ C ˆ N)PdBr: [Methyl(N ˆ C ˆ N)PdBr], C26H25N4PdBr (14), [Tosyl(N ˆ C ˆ N)PdBr], C38H33N4O4S2PdBr (15), [ Benzyl(N ˆ C ˆ N)PdBr], C38H33N4PdBr (16) and [Pentyl(N ˆ C ˆ N)PdBr], C34H41N4PdBr (17) [(N ˆ C ˆ N) = 5-tert-butyl-1,3-bis-(N-substituted-benzimidazol-2′-yl)phenyl] were synthesized by the treatment of palladium(0) precursor, Pd2(dba)3 with 5-tert-butyl-1,3-bis-(N-substituted-benzimidazol-2′-yl)-2-bromobenzenes (10–13) via oxidative addition with chemical yield of 46–70%. Complex 15 decomposed in [D6]DMSO to yield the protic palladacycle 18, [ H(N ˆ C ˆ N)PdBr], C24H21N4PdBr, which was confirmed by the time-dependent 1H NMR studies, IR spectroscopy, mass spectrometry and the structure was corroborated with X-ray crystallographic studies. Complexes 14–18 are the fully characterized examples of NCN palladium(II) pincer complexes incorporating the N-substituted-5-tert-butyl-1,3-bis-(benzimidazol-2′-yl)-2-bromobenzene framework. The palladium(II) pincer complexes have been studied for C-H functionalization of benzyl nitriles with N-tosylaldimines to form β-aminonitriles.

Source: Journal of Organometallic Chemistry - February 2, 2018 Category: Chemistry Source Type: research