NO disproportionation reactivity of Fe tropocoronand complexes
The synthesis and characterization of divalent [Fe(TC-5,5)] (1) and trivalent [Fe(OTf)(TC-5,5)] (2) tropocoronand complexes are described. Compound 1 reacts with 1 equiv of NO to form the {l{underscore}brace}FeNO{r{underscore}brace}{sup 7} complex 3. A single-crystal X-ray structure determination of 3 reveals a trigonal bipyramidal geometry with a linearly coordinated nitrosyl (Fe-N-O = 174.3(4){degree}) having a short Fe-N distance of 1.670(4) {angstrom}. EPR and Moessbauer spectroscopy, SQUID susceptometry, and normal coordinate analysis indicate 3 to be a low-spin {l{underscore}brace}Fe{sup III}(NO{sup {minus}}){r{underscore}brace}{sup 2+} species. In the presence of excess NO, 3 converts to a metastable nitrosyl-nitrito complex that decomposes by losing NO{sub 2}, which subsequently nitrates the aromatic tropolone rings of the ligand. The final products of the NO disproportionation reaction are N{sub 2}O and [Fe(NO)(TC-5,5-NO{sub 2})] (4). The {nu}{sub NO} stretching band of 4 is increased to 1,716 cm{sup {minus}} from its value of 1,692 cm{sup {minus}} in 3, owing to the electron-withdrawing nitro groups on the ligand, and the compound no longer promotes the disproportionation of NO. Mechanistic aspects of the reaction are discussed.
- Research Organization:
- Massachusetts Inst. of Tech., Cambridge, MA (US)
- OSTI ID:
- 20013692
- Journal Information:
- Journal of the American Chemical Society, Vol. 121, Issue 45; Other Information: PBD: 17 Nov 1999; ISSN 0002-7863
- Country of Publication:
- United States
- Language:
- English
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