Reaction of an iron(IV) nitrido complex with cyclohexadienes: cycloaddition and hydrogen-atom abstraction

Inorg Chem. 2014 Aug 18;53(16):8425-30. doi: 10.1021/ic5010006. Epub 2014 Jul 28.

Abstract

The iron(IV) nitrido complex PhB(MesIm)3Fe≡N reacts with 1,3-cyclohexadiene to yield the iron(II) pyrrolide complex PhB(MesIm)3Fe(η(5)-C4H4N) in high yield. The mechanism of product formation is proposed to involve sequential [4 + 1] cycloaddition and retro Diels-Alder reactions. Surprisingly, reaction with 1,4-cyclohexadiene yields the same iron-containing product, albeit in substantially lower yield. The proposed reaction mechanism, supported by electronic structure calculations, involves hydrogen-atom abstraction from 1,4-cyclohexadiene to provide the cyclohexadienyl radical. This radical is an intermediate in substrate isomerization to 1,3-cyclohexadiene, leading to formation of the pyrrolide product.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Cyclization
  • Cyclohexenes / chemistry*
  • Hydrogen / chemistry*
  • Iron Compounds / chemical synthesis*
  • Iron Compounds / chemistry*
  • Molecular Conformation
  • Nitrogen Compounds / chemistry*

Substances

  • Cyclohexenes
  • Iron Compounds
  • Nitrogen Compounds
  • Hydrogen