sulfur-functionalized n-heterocyclic carbene complexes of pd(ii) syntheses, structures and catalytic activitiessulfur-functionalized pd(ii)的氮杂卡宾配合物合成、结构和催化活动.pdf

Molecules 2012, 17, 2491-2517; doi:10.3390/molecule OPEN ACCESS molecules ISSN 1420-3049 /journal/molecules Review Sulfur-Functionalized N-Heterocyclic Carbene Complexes of Pd(II): Syntheses, Structures and Catalytic Activities Dan Yuan and Han Vinh Huynh * Department of Chemistry, 3 Science Drive 3, National University of Singapore, 117543, Singapore; E-Mail: g0700466@.sg * Author to whom correspondence should be addressed; E-Mail: chmhhv@.sg; Tel.: +65-6516-2670; Fax: +65-6779-1691. Received: 1 February 2012; in revisedform: 20 February 2012 / Accepted: 23 February 2012 / Published: 1 March 2012 Abstract: N-heterocyclic carbenes (NHCs) can be easily modified by introducing functional groups at the nitrogen atoms, which leads to versatile coordination chemistry as well as diverse catalytic applications of the resulting complexes. This article summarizes our contributions to the field of NHCs bearing different types of sulfur functions, i.e., thioether, sulfoxide, thiophene, and thiolato. The experimental evidence for the truly hemilabile coordination behavior of a Pd(II) thioether-NHC complex has been reported as well. In addition, complexes bearing rigid CSC-pincer ligands have been synthesized and the reasons for pincer versus pseudo-pincer formation investigated. Incorporation of the electron-rich thiolato function resulted in the isolation of structurally diverse complexes. The catalytic activities of selected complexes have been tested in Suzuki-Miyau