Cyclometalated and alkoxyphenyl-substituted palladium imidazolin-2-ylidene complexes: synthetic, structural, and catalytic studies

Stylianides, N., Danopoulos, A.A., Pugh, D., Hancock, F. and Zanotti-Gerosa, A. (2007) Cyclometalated and alkoxyphenyl-substituted palladium imidazolin-2-ylidene complexes: synthetic, structural, and catalytic studies. Organometallics, 26 (23), 5627-5635. (doi:10.1021/om700603d).

Abstract

Some new N,N'-bis(aryl)imidazolinium salts (3a-h), in which the N-aryl groups have one unsubstituted ortho position and alkyl (Me, Pri) or alkoxy (OMe, OPri) substitution at the other ortho and/or para positions, have been prepared. They were used for the synthesis of N-heterocyclic carbene complexes of palladium in which the N-heterocyclic carbene is attached to cyclometalated or electron-rich aromatic rings (4, 5, 11d,e). The reaction of Pd(tmed)(CH3)2 with the N-heterocyclic carbene generated from 3b and base gave the dimethyl complex 6, which quantitatively eliminated ethane to form the Pd(0) complex 7. The latter was converted to a new type of "pincer" complex (8) by facile cyclometalation of both aromatic groups of the N-heterocyclic carbene ligand. The activities of the new complexes 4 and 9d,e in the Heck reaction of aryl halides were compared. At higher temperatures the complexes 9d,e show low activity in the coupling of aryl chlorides.

This record has no associated files available for download.

Contributors

Download statistics