First [Fe-NO](6) complex with an N(2)S(3)Fe-NO core as a model of NO-inactivated iron-containing nitrile hydratase. Are thiolates and thioethers equivalent donors in low-spin iron complexes?

Inorg Chem. 2002 Mar 11;41(5):1039-41. doi: 10.1021/ic015629x.

Abstract

The spectroscopic and structural properties of [(bmmp-TASN)FeNO]BPh(4) (1) (bmmp-TASN = 4,7-bis(2'-methyl-2'-mercaptopropyl)-1-thia-4,7-diazacyclononane) have been determined and are compared with the nitric oxide inactivated form of iron-containing nitrile hydratase, NHase(dark). [(bmmp-TASN)FeNO]BPh(4) is prepared from the addition of NO to (bmmp-TASN)FeCl followed by addition of sodium tetraphenylborate. [(bmmp-TASN)FeNO]BPh(4) crystallizes from acetonitrile-methanol solutions upon ether vapor diffusion as dark blue plates in the monoclinic space group P2(1)/c with a = 11.9521(14) A, b = 11.3238(13) A, c = 26.624(3) A, beta = 98.280(2), and Z = 4. The nu(NO) stretching frequency of 1856 cm(-)(1) and the Mössbauer parameters, delta = 0.06 mm/s and DeltaE(q) = 1.75 mm/s, compare favorably with those of NHase(dark). The similarities of the iron-sulfur bond distances to the thiolate, 2.284(2) A and 2.291(2) A, versus thioether, 2.285(2) A, are attributed to the low-spin configuration of the iron. The relationship between this structural observation and the spectroscopic properties of the complex are discussed.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Catalysis
  • Crystallography, X-Ray
  • Hydro-Lyases / chemistry*
  • Hydro-Lyases / metabolism
  • Iron Compounds / chemistry*
  • Iron Compounds / metabolism
  • Ligands
  • Models, Chemical
  • Molecular Conformation
  • Molecular Structure
  • Nitric Oxide / chemistry*
  • Oxidation-Reduction
  • Structure-Activity Relationship
  • Sulfur Compounds / chemistry*
  • Sulfur Compounds / metabolism

Substances

  • Iron Compounds
  • Ligands
  • Sulfur Compounds
  • Nitric Oxide
  • Hydro-Lyases
  • nitrile hydratase