Mono- and dinuclear palladium(II) N,S-heterocyclic carbene complexes with N spacers and their Suzuki coupling activities

Swee Kuan Yen; Lip Lin Koh; Han Vinh Huynh; T S Andy Hor

doi:10.1002/asia.200800177

Mono- and dinuclear palladium(II) N,S-heterocyclic carbene complexes with N spacers and their Suzuki coupling activities

Chem Asian J. 2008 Sep 1;3(8-9):1649-56. doi: 10.1002/asia.200800177.

Authors

Swee Kuan Yen¹, Lip Lin Koh, Han Vinh Huynh, T S Andy Hor

Affiliation

¹ Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.

PMID: 18613208
DOI: 10.1002/asia.200800177

Abstract

Mixed-ligand N,S-heterocyclic carbene (NSHC) complexes, trans-[PdBr(2)(NSHC)(Py)] (NSHC=3-benzyl- or 3-propyl-benzothiazolin-2-ylidene), have been obtained from bridge-cleavage reactions of the dinuclear complex, [Pd(mu-Br)Br(NSHC)](2), in pyridine at room temperature. Use of neutral N-bidentate donors (L=pyrazine, 1,2-bis(4-pyridyl)ethane, 4,4'-bipyridine and trans-1,2-bis(4-pyridyl)ethylene) yields the dinuclear spacer-bridged [Pd(2)Br(4)(NSHC)(2)(mu-L)] complexes. The X-ray single-crystal structures of the pyridyl, bridging pyrazine and 1,2-bis(4-pyridyl)ethane complexes are reported. These air-stable complexes are active in the Suzuki-Miyaura coupling reactions of selected aryl bromides. The dinuclear complexes are generally more active than their mononuclear pyridyl analogues. The benzyl derivatives consistently outperform the n-propyl counterparts.