Bis(diisopropylphosphino)pyridine Iron Dicarbonyl, Dihydride, and Silyl Hydride Complexes

Ryan J. Trovitch, Emil Lobkovsky, and Paul J. Chirik*
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853
Inorg. Chem., 2006, 45 (18), pp 7252–7260
DOI: 10.1021/ic0608647
Publication Date (Web): August 5, 2006
Copyright © 2006 American Chemical Society
*

 To whom correspondence should be addressed. E-mail:  pc92@ cornell.edu.

Abstract

Abstract Image

Treatment of the bis(diisopropylphosphino)pyridine iron dichloride, (iPrPNP)FeCl2 (iPrPNP = 2,6-(iPr2PCH2)2(C5H3N)), with 2 equiv of NaBEt3H under an atmosphere of dinitrogen furnished the diamagnetic iron(II) dihydride dinitrogen complex, (iPrPNP)FeH2(N2). Addition of 1 equiv of PhSiH3 to (iPrPNP)FeH2(N2) resulted in exclusive substitution of the hydride trans to the pyridine to yield the silyl hydride dinitrogen compound, (iPrPNP)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 (iPrPNP)FeH2(N2) and (iPrPNP)FeH(SiH2Ph)N2 form η2-dihydrogen complexes upon exposure to H2. The iron hydrides and the η2-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.

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History

  • Published In Issue September 04, 2006
  • Received May 18, 2006

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