Three-Coordinate Iron(II) Expanded Ring N-Heterocyclic Car-bene Complexes

Research output: Contribution to journalArticle

  • External authors:
  • Jay Dunsford
  • Thomas Pugh
  • Sachin Shah
  • David Evans

Abstract

A sterically demanding 7-membered expanded ring N-heterocyclic carbene (NHC) ligand allows access to rare examples of 3-coordinate iron(II)-NHC complexes incorporating only halide co-ligands of the general formulae, [Fe(NHC)X2] (NHC = 7-DiPP, X = Br or Cl), 1 and 2, respectively. Reducing the steric influence of the ancillary NHC ligand through modulation of the N-aryl substituents leads to either 4- or 3-coordinate complexes of the general formula, [Fe(NHC)Br2(THF)], 3 or [Fe(NHC)Br2], 4 (NHC = 7-Mes) dependent upon the solvent of recrystallization. The further reduction of NHC steric influence results in 4-coordinate geometries at iron in the form of either the dimeric species, [Fe(NHC)Br(μ-Br)]2, 5 or [Fe(NHC)Br2(THF)], 6 (NHC = SDiPP), again dependent upon the solvent of recrystallization. The series of compounds 1-6 have been analyzed by 1H NMR spectroscopy, X-ray crystallography, elemental microanalysis, Mössbauer spectroscopy (for 1, 3-5) and Evans method magnetic susceptibility. In addition to these measurements the 3-coordinate species 1 and 4 have been further analyzed by SQUID magnetometry and CASSCF calculations which show significant magnetic anisotropy that is extremely sensitive to the coordination geometry.

Bibliographical metadata

Original languageEnglish
JournalOrganometallics
Early online date14 Apr 2016
DOIs
StatePublished - 2016