Bis(diisopropylphosphino)pyridine iron dicarbonyl, dihydride, and silyl hydride complexes

Inorg Chem. 2006 Sep 4;45(18):7252-60. doi: 10.1021/ic0608647.

Abstract

Treatment of the bis(diisopropylphosphino)pyridine iron dichloride, ((iPr)PNP)FeCl2 ((iPr)PNP = 2,6-(iPr2PCH2)2(C5H3N)), with 2 equiv of NaBEt3H under an atmosphere of dinitrogen furnished the diamagnetic iron(II) dihydride dinitrogen complex, ((iPr)PNP)FeH2(N2). Addition of 1 equiv of PhSiH3 to ((iPr)PNP)FeH2(N2) resulted in exclusive substitution of the hydride trans to the pyridine to yield the silyl hydride dinitrogen compound, ((iPr)PNP)FeH(SiH2Ph)N2, which has been characterized by X-ray diffraction. The solid-state structure established a distorted octahedral geometry where the hydride ligand distorts toward the iron silyl. Both ((iPr)PNP)FeH2(N2) and ((iPr)PNP)FeH(SiH2Ph)N2 form eta2-dihydrogen complexes upon exposure to H2. The iron hydrides and the eta2-H2 ligands are in rapid exchange in solution, consistent with the previously reported "cis" effect, arising from a dipole/induced dipole interaction between the two ligands. Taken together, the spectroscopic, structural, and reactivity studies highlight the relative electron-donating ability of this pincer ligand as compared to the redox-active aryl-substituted bis(imino)pyridines.

MeSH terms

  • Catalysis
  • Crystallography, X-Ray
  • Ferric Compounds / chemical synthesis
  • Ferric Compounds / chemistry*
  • Hydrogen / chemistry*
  • Ketones / chemistry*
  • Ligands
  • Models, Molecular
  • Molecular Structure
  • Organometallic Compounds / chemistry*
  • Silanes / chemistry*
  • Stereoisomerism

Substances

  • Ferric Compounds
  • Ketones
  • Ligands
  • Organometallic Compounds
  • Silanes
  • Hydrogen