Synthesis and catalytic application of cyclopentadienyl nickel(II) N-heterocyclic carbene complexes

Abstract

A series of ester-functionalized benzimidazolium salts 2a–c were prepared by quaternization of 1-{(ethoxycarbonyl)methyl}benzimidazole (1) with 3,5-dimethylbenzyl bromide, 2,5-dimethylbenzyl chloride and 3-methoxybenzyl chloride, respectively. Refluxing 2a–c with nickelocene in THF yielded the neutral cyclopentadienyl NHC nickel(II) complexes 3a–c. Their structures were defined by NMR, IR and elemental analysis techniques. Molecular weights of 3a–c were affirmed by MALDI-TOF mass spectrometry. Catalytic tests of 3a–c were performed in Kumada coupling of some aryl chlorides with phenylmagnesium bromide at 25 °C.

Graphical Abstract

Keywords:

• N-Heterocyclic carbene
• benzimidazolium
• nickel
• Kumada coupling
• catalysis

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by Scientific Research Project of Manisa Celal Bayar University (MCBU BAP: 2014/3).