Bis(diisopropylphosphino)pyridine iron dicarbonyl, dihydride, and silyl hydride complexes.
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.
Trovitch
Ryan J
RJ
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, NY 14853, USA.
Lobkovsky
Emil
E
Chirik
Paul J
PJ
D002384:Catalysis; D018360:Crystallography, X-Ray; D005290:Ferric Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D008024:Ligands; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000737:chemistry*; D012821:Silanes / Q000737:chemistry*; D013237:Stereoisomerism
D005290:Ferric Compounds; D007659:Ketones; D008024:Ligands; D009942:Organometallic Compounds; D012821:Silanes; D006859:Hydrogen