New pentamethylene-bridged bis-imidazolium dication ligands and its palladium(II) complexes: Synthesis, characterization, and catalysis

作者：Trivedi Manoj^*; Nagarajan R; Rath Nigam P; Kumar Abhinav; Molloy Kieran C; Kociok Koehn Gabriele

来源：Inorganica Chimica Acta, 2012, 383: 118-124.

DOI：10.1016/j.ica.2011.10.065

• Imidazolium dication ligand
• Palladium complex
• Crystal structure
• Weak interaction
• Catalysis

Two new pentamethylene-bridged bis-imidazolium dication ligands (L-1 = 1,5-bis(1-(4-cyanophenyl)imidazolium-1-yl) pentane dibromide) and L-2 = 1,5-bis(1-(4-methoxyphenyl)-imidazolium-1-yl)pentane dibromide) bearing CPI (1-(4-cyanophenyl)-imidazole) and MPI (1-(4-methoxyphenyl)-1H-imidazole)functionality have been prepared via the reaction of 1,5-dibromopentane with a substituted imidazole derivative. The imidazolium ligand L-1 and L-2 on reaction with [PdBr2(C6H5CN)(2)] led to the formation of neutral bis-imidazolium dication palladium(II) complexes [L-1] [PdBr4] [1] (L-1 = 1,5-bis(1-(4-cyanophenylimidazolium-1-yl) pentane) and [L-2] [PdBr4] [2] (L-2 = 1,5-bis(1-(4-methoxyphenyl) imidazolium-1-yl) pentane), respectively. The new ligands as well as their palladium(II) complexes, has been characterized by elemental analysis, electronic, IR, H-1 and C-13 NMR, FAB-MS and ESI-MS spectroscopy. The molecular structure of the representative complex [L-2] [PdBr4] [2] have been determined by single crystal X-ray analysis. Complex 2 exhibits the strong intra-and inter-molecular C-H center dot center dot center dot X (X = Br, O, pi) weak interactions, which plays an important role in stabilizing the crystal packing. Furthermore, the C-H center dot center dot center dot O interactions in 2 lead to a single-helical motif. The complexes 1 and 2 exhibited good activity in a model Suzuki-Miyaura coupling reaction.

• 出版日期2012-3-30