کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1325837 | 1499911 | 2013 | 6 صفحه PDF | دانلود رایگان |
A divalent cobalt iodine complex bearing 1,3-bis(mesityl)imidazol-2-ylidene and pyridine ligands was synthesized and its structure was determined. The cobalt center has a typical d7-tetrahedral geometry, as expected. Catalytic application of this cobalt complex with bromoalkanes and Grignard reagents demonstrated high-yield formation of alkenes as a result of β-hydrogen elimination; in sharp contrast, the activation of alkyl halides was not successful using the larger N-heterocyclic carbene ligand, 1,3-bis(2,6-diisopropyl-phenyl)imidazol-2-ylidene. In the presence of styrene, Heck reaction proceeded with trans selectivity. The reaction of a substrate containing a bromobenzyl moiety yielded a homocoupling product.
A divalent cobalt iodine complex bearing 1,3-bis(mesityl)imidazol-2-ylidene and pyridine ligands was synthesized and characterized. Catalytic applications of this complex with 1-bromooctane and Grignard reagents gave β-elimination or Heck reaction products. The reaction of 1-bromofluorene yielded a homocoupling product, suggesting benzyl radical formation.Figure optionsDownload as PowerPoint slideHighlights
► A new divalent cobalt complex with a NHC ligand was prepared and determined.
► The cobalt complex is active toward C–Br bond activation of alkyl bromides.
► β-Elimination, Heck reaction and homo-coupling reaction products were obtained.
Journal: Journal of Organometallic Chemistry - Volume 727, 1 March 2013, Pages 44–49