کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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1306706 | 975099 | 2010 | 12 صفحه PDF | دانلود رایگان |
The chelating ligand tris-[2-(3-aryl-imidazol-2-ylidene)ethyl]amine (TIMENR, R = aryl = 2,6-xylyl (xyl), mesityl (mes)) has provided access to reactive transition metal complexes. Here, two new tripodal N-heterocyclic carbene ligands of the TIMENR system (R = aryl = tolyl (tol), 3,5-xylyl (3,5xyl)), featuring sterically less demanding aryl substituents were synthesized. With these ligands, Fe(II) precursor complexes could be obtained, namely [(TIMENtol)Fe](BF4)2 (3) and [(TIMEN3,5xyl)Fe(CH3CN)](PF6)2 (7), which showed unexpected reactivity upon reduction. Treatment of the compounds with sodium amalgam yield the tris- and bis-metallated products, [(TIMENtol∗∗∗)Fe] (4) and [(TIMEN3,5xyl∗∗)Fe] (8), respectively. While the Fe(III) complex 4 is relatively inert towards oxygen, the Fe(II) complex 8 is prone to oxidation. This oxidation of 8 can readily be observed in chlorinated solvents, producing the Fe(III) complex [(TIMEN3,5xyl∗∗)Fe](PF6) (9). All new ligand imidazolium precursors and metal complexes were characterized by single crystal X-ray structure determination.
New tripodal NHC ligands of the TIMENR system (R = aryl = tolyl (tol), 3,5-xylyl (3,5xyl)) were synthesized. With these ligands the Fe(II) precursor complexes [(TIMENtol)Fe](BF4)2 (3) and [(TIMEN3,5xyl)Fe(CH3CN)](PF6)2 (7) could be obtained, which showed unexpected reactivity upon reduction. All new ligand imidazolium precursors and metal complexes were characterized by single crystal X-ray structure determination.Figure optionsDownload as PowerPoint slide
Journal: Inorganica Chimica Acta - Volume 364, Issue 1, 15 December 2010, Pages 226–237