Palladium, rhodium and platinum complexes of ortho-xylyl-linked bis-N-heterocyclic carbenes: Synthesis, structure and catalytic activity

New Pd(II), Pt(II) and Rh(I) N-heterocyclic carbene (NHC) complexes containing two NHC units linked by an ortho-xylyl group are described and structurally and spectroscopically characterised. The Pt(II) complexes represent the first examples of Pt-bis(NHC) complexes where the NHC units are linked by an ortho-xylyl group. Functionalisation of the bis(NHC) ligands with heptyl groups has been used as a means of enhancing the solubility of the complexes, in order to facilitate spectroscopic characterisation and catalytic studies. The catalytic activity of the palladium(II) complexes in Heck and Suzuki cross-coupling reactions has been examined to investigate any effects of the diverse structural changes, though these appear to be insignificant.

Graphical abstractNew Pd(II), Pt(II) and Rh(I) complexes that contain two NHC units linked by an ortho-xylyl group are described and structurally and spectroscopically characterised. The catalytic activity of the Pd(II) complexes in Heck and Suzuki cross-coupling reactions has been examined to investigate any effects of the structural changes in the NHC-ligand framework.Figure optionsDownload full-size imageDownload as PowerPoint slide