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Updated: Jun 19, 2026

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Studies on bis(halogeno) dioxomolybdenum(VI)-bipyridine complexes: synthesis and catalytic activity
Alev Günyar1, Ming-Dong Zhou, Markus Drees
1Molecular Catalysis, Catalysis Research Centre, Technische Universität München, Lichtenbergstrasse 4, D-85747, Garching, Germany.
Abstract:
Dioxomolybdenum(VI) complexes with the general formula [MoO2Cl2L2] (L2=3,3'-dimethyl-2,2'-bipyridine, 5,5'-dimethyl-2,2'-bipyridine, 6,6'-dimethyl-2,2'-bipyridine, 4,4'-dibromo-2,2'-bipyridine, 5,5'-dibromo-2,2'-bipyridine, 5,5'-diamino-2,2'-bipyridine; 5,5'-dinitro-2,2'-bipyridine; 5,5'-di-ethoxycarbonyl-2,2'-bipyridine; 6-phenyl-2,2'-bipyridine; 2,2':6',2''-terpyridine) have been prepared and characterised. [MoO2Cl2(5,5'-di-ethoxycarbonyl-2,2'-bipyridine)] has been examined by single crystal X-ray analysis. The complexes were applied as homogenous catalysts for the epoxidation of cyclooctene with tert-butyl hydroperoxide (TBHP) as oxidising agent. The new compounds show an overall high activity and are highly selective catalysts in the epoxidation of cyclooctene. The stability of the complexes and differences in the catalytic activity can be clearly attributed to electronic contributions of the functional groups on bipyridine ligands and to steric restrictions. DFT calculations have assisted in a better understanding of the stability of the complexes and are in agreement with experiment. The influence of the terminal oxo ligands and the Lewis base ligands on the Mo center keep the compounds on quite a stable level of electron density.
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