Raman Signature of the Fe2O2 "Diamond" Core
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- 作者：Elizabeth C. Wilkinson ; Yanhong Dong ; Yan Zang ; Hiroshi Fujii ; Robert Fraczkiewicz ; Grazyna Fraczkiewicz ; Roman S. Czernuszewicz ; and Lawrence Que ; Jr.
- 刊名：Journal of the American Chemical Society
- 出版年：1998
- 出版时间：February 11, 1998
- 年：1998
- 卷：120
- 期：5
- 页码：955 - 962
- 全文大小：369K
- 年卷期：v.120,no.5(February 11, 1998)
- ISSN：1520-5126
文摘
We report the resonance Raman (RR) spectra of iron complexescontaining the Fe2(
-O)2 core.Frozen CH3CN solutions of theFeIIIFeIV intermediate[Fe2(-O)2L2](ClO4)3(where L = TPA, 5-Me3-TPA,5-Me2-TPA, 5-MeTPA, 5-Et3-TPA, or3-Me3-TPA) show numerous resonance-enhanced vibrations, andamongthese, an oxygen-isotope-sensitive vibration around 667cm-1 that shifts ca. 30cm-1 when the samples areallowed to exchange with 18OH2, and whoseRaman shift does not vary with methyl substitution of theTPAligand. Spectra of iron-isotope-substituted samples of[Fe2(-O)2(L)2](ClO4)3(54Fe and 57Fe for L =TPA,and 54Fe and 58Fe for L =5-Me3-TPA) show that this vibration is alsoiron-isotope-sensitive. These isotopicdata taken together strongly suggest that this vibration involvesmotion of the Fe2(-O)2 core that isisolatedfrom motions of the ligand. A frozen CH3CNsolution of the diiron(III) complex[Fe2(-O)2(6-Me3-TPA)2](ClO4)2 shows one intense resonance-enhancedvibration at 692 cm-1 that shifts -30cm-1 with 18Olabeling.Normal coordinate analysis of theFe2(-O)2 core in[Fe2(-O)2(5-Me3-TPA)2](ClO4)3supports the assignmentof the Fermi doublet centered around 666.2cm-1 as an A1 vibration of thiscore. Furthermore, we proposethat this unique feature found in the region between 650 and 700cm-1 is indicative of a diamond corestructureand is the Raman signature of an iron cluster containing thiscore.
-O)2 core.Frozen CH3CN solutions of theFeIIIFeIV intermediate[Fe2(-O)2L2](ClO4)3(where L = TPA, 5-Me3-TPA,5-Me2-TPA, 5-MeTPA, 5-Et3-TPA, or3-Me3-TPA) show numerous resonance-enhanced vibrations, andamongthese, an oxygen-isotope-sensitive vibration around 667cm-1 that shifts ca. 30cm-1 when the samples areallowed to exchange with 18OH2, and whoseRaman shift does not vary with methyl substitution of theTPAligand. Spectra of iron-isotope-substituted samples of[Fe2(-O)2(L)2](ClO4)3(54Fe and 57Fe for L =TPA,and 54Fe and 58Fe for L =5-Me3-TPA) show that this vibration is alsoiron-isotope-sensitive. These isotopicdata taken together strongly suggest that this vibration involvesmotion of the Fe2(-O)2 core that isisolatedfrom motions of the ligand. A frozen CH3CNsolution of the diiron(III) complex[Fe2(-O)2(6-Me3-TPA)2](ClO4)2 shows one intense resonance-enhancedvibration at 692 cm-1 that shifts -30cm-1 with 18Olabeling.Normal coordinate analysis of theFe2(-O)2 core in[Fe2(-O)2(5-Me3-TPA)2](ClO4)3supports the assignmentof the Fermi doublet centered around 666.2cm-1 as an A1 vibration of thiscore. Furthermore, we proposethat this unique feature found in the region between 650 and 700cm-1 is indicative of a diamond corestructureand is the Raman signature of an iron cluster containing thiscore.