Catalytically Active -Oxodiiron(IV) Oxidants from Iron(III) and Dioxygen
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- 作者：Anindya Ghosh ; Filipe Tiago de Oliveira ; Toshihiro Yano ; Takanori Nishioka ; Evan S. Beach ; Isamu Kinoshita ; Eckard Mü ; nck ; Alexander D. Ryabov ; Colin P. Horwitz ; and Terrence J. Collins
- 刊名：Journal of the American Chemical Society
- 出版年：2005
- 出版时间：March 2, 2005
- 年：2005
- 卷：127
- 期：8
- 页码：2505 - 2513
- 全文大小：234K
- 年卷期：v.127,no.8(March 2, 2005)
- ISSN：1520-5126
文摘
The reaction between an FeIII complex and O2 to afford a stable catalytically active diiron(IV)-
-oxo compound is described. Phosphonium salts of orange five-coordinated FeIII-TAML complexes withan axial aqua ligand ([PPh4]1-H2O, tetraamidato macrocyclic FeIII species derived from 3,3,6,6,9,9-hexamethyl-3,4,8,9-tetrahydro-1H-1,4,8,11-benzotetraazacyclotridecine-2,5,7,10(6H,11H)-tetraone) reactrapidly with O2 in CH2Cl2 or other weakly coordinating solvents to produce black -oxo-bridged diiron(IV)complexes, 2, in high yields. Complexes 2 have been characterized by X-ray crystallography (2 cases),microanalytical data, mass spectrometry, UV/Vis, Mössbauer, and 1H NMR spectroscopies. Mössbauerdata show that the diamagnetic Fe-O-Fe unit contains antiferromagnetically coupled S = 1 FeIV sites;diamagnetic 1H NMR spectra are observed. The oxidation of PPh3 to OPPh3 by 2 was confirmed by UV/Vis and GC-MS. Labeling experiments with 18O2 and H218O established that the bridging oxygen atom of2 derives from O2. Complexes 2 catalyze the selective oxidation of benzylic alcohols into the correspondingaldehydes and bleach rapidly organic dyes, such as Orange II in MeCN-H2O mixtures; reactivity evidencesuggests that free radical autoxidation is not involved. This work highlights a promising development forthe advancement of green oxidation technology, as O2 is an abundant, clean, and inexpensive oxidizingagent.
-oxo compound is described. Phosphonium salts of orange five-coordinated FeIII-TAML complexes withan axial aqua ligand ([PPh4]1-H2O, tetraamidato macrocyclic FeIII species derived from 3,3,6,6,9,9-hexamethyl-3,4,8,9-tetrahydro-1H-1,4,8,11-benzotetraazacyclotridecine-2,5,7,10(6H,11H)-tetraone) reactrapidly with O2 in CH2Cl2 or other weakly coordinating solvents to produce black -oxo-bridged diiron(IV)complexes, 2, in high yields. Complexes 2 have been characterized by X-ray crystallography (2 cases),microanalytical data, mass spectrometry, UV/Vis, Mössbauer, and 1H NMR spectroscopies. Mössbauerdata show that the diamagnetic Fe-O-Fe unit contains antiferromagnetically coupled S = 1 FeIV sites;diamagnetic 1H NMR spectra are observed. The oxidation of PPh3 to OPPh3 by 2 was confirmed by UV/Vis and GC-MS. Labeling experiments with 18O2 and H218O established that the bridging oxygen atom of2 derives from O2. Complexes 2 catalyze the selective oxidation of benzylic alcohols into the correspondingaldehydes and bleach rapidly organic dyes, such as Orange II in MeCN-H2O mixtures; reactivity evidencesuggests that free radical autoxidation is not involved. This work highlights a promising development forthe advancement of green oxidation technology, as O2 is an abundant, clean, and inexpensive oxidizingagent.