Normal and abnormal carbene complexes derived from thiazole: Preparation and a preliminary investigation of their relative catalytic performance

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• 作者：Elzet Stander-Grobler^a ; Oliver Schuster^a ;   ; ^b ; Christoph E. Strasser^a ; Martin Albrecht^b ; Stephanie Cronje^a ;   ; ^c ; Helgard G. Raubenheimer^a ;   ; ^{hgr@sun.ac.za}
• 关键词：NHC ; Remote azolylidene ; Group 10 ; Azolylidene ; Palladium ; Nickel ; Five-membered heterocycle ; Carbene complex
• 刊名：Polyhedron
• 出版年：2011
• 出版时间：3 November 2011
• 年：2011
• 卷：30
• 期：17
• 页码：2776-2782
• 全文大小：564 K

文摘

Readily prepared 2-, 4- and 5-bromo-3-methyl thiazolium triflates react by oxidative substitution with M(PPh₃)₄ (M = Ni or Pd) to furnish five of the expected normal and abnormal cationic thiazolylidene complexes (1a, 1b, 2a, 2b, and 3b). Carbene complex formation is accompanied by a ca. 40 ppm downfield shift of the ¦Á-N carbene carbons in Pd complexes 1 and 2 in their ¹³C NMR spectra but the chemical shift of C(carbene) in the abnormal 3b (¦Ä 135.7) is particularly low. Crystal and molecular structures of complexes 1a, 2b, and 3b all indicate a square planar arrangement of the ligands around the central metal atoms. The new complexes catalyse Suzuki¨CMiyaura aryl coupling.