Palladium(ii) complexes with electron-poor, 4,5-disubstituted diimidazol-2-ylidene ligands: synthesis, characterization and catalytic activityElectronic supplementary information (ESI) available: NMR spectra of the compounds, additional X-ray crystallographic details and cif files for complexes 3a, 3b, 3c and 3e. CCDC 1054314-1054317. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c5dt01067e

• Main Authors: Pinter, Piermaria, Biffis, Andrea, Tubaro, Cristina, Tenne, Mario, Kaliner, Maria, Strassner, Thomas
• Format: Journal Article
• Language: English
• Published: 12.05.2015
• ISSN: 1477-9226; 1477-9234
• DOI: 10.1039/c5dt01067e

Diimidazolium salts featuring different bridges between the imidazolium groups, as well as electron-withdrawing groups (chloride, cyanide) at the 4- and 5-position of the heterocyclic rings, have been successfully prepared. The diimidazolium salts serve as convenient precursors of di(N-heterocyclic carbene) ligands, which coordinate in a chelating fashion to palladium( ii ) centres. The effect of the newly introduced electron-withdrawing groups on the spectroscopic and structural characteristics of the resulting complexes as well as on their reactivity as catalysts in a model alkyne hydroarylation reaction has been investigated and is discussed herein. Palladium( ii ) complexes with N-heterocyclic dicarbene ligands featuring electron-withdrawing substituents have been prepared and tested as catalysts in alkyne hydroarylations.