NO disproportionation reactivity of Fe tropocoronand complexes

Published

Journal Article

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 {FeNO}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)°) having a short Fe-N distance of 1.670(4) Å. EPR and Mossbauer spectroscopy, SQUID susceptometry, and normal coordinate analysis indicate 3 to be a low-spin {Fe(III)(NO-)}2+ species. In the presence of excess NO, 3 converts to a metastable nitrosyl-nitrito complex that decomposes by losing NO2, which subsequently nitrates the aromatic tropolone rings of the ligand. The final products of the NO disproportionation reaction are N2O and [Fe(NO)(TC-5,5-NO2)] (4). The v(NO) stretching band of 4 is increased to 1716 cm-1 from its value of 1692 cm-1 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.

Full Text

Duke Authors

Cited Authors

  • Franz, KJ; Lippard, SJ

Published Date

  • November 17, 1999

Published In

Volume / Issue

  • 121 / 45

Start / End Page

  • 10504 - 10512

International Standard Serial Number (ISSN)

  • 0002-7863

Digital Object Identifier (DOI)

  • 10.1021/ja991664f

Citation Source

  • Scopus