Electronic Properties of Bis(η5-cyclopentadienyl)titanium 2,2'-Bipyridyl. A Singlet Molecule with a Low-Lying Triplet Excited State1

Arlene Mootz McPherson, Benjamin F. Fieselmann, Dennis L. Lichtenberger, Galen D. Stucky, Gary L. McPherson

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55 Scopus citations


Magnetic susceptibility and EPR studies show that (η5-C5H5)2Ti(bpy) has a triplet excited state which is thermally accessible from the ground-state singlet. The temperature dependence of the magnetic susceptibility and the EPR spectra was measured and confirms that the singlet and triplet states are separated by approximately 600 cm-1 in toluene solution and 750 cm-1 in the solid state. In both solution and solid state (η5-C5H5)2Ti(bpy) is monomeric so that the presence of extended Ti-Ti interactions is unlikely. The low-lying triplet most likely corresponds to a state in which one unpaired electron formally occupies a molecular orbital which is localized on (η5-C5H5)2Ti while a second unpaired electron resides in the lowest energy π* orbital of the bipyridyl group. This conclusion is supported by Fenske-Hall molecular orbital calculations. The calculations and single crystal X-ray data also suggest that the preferred molecular geometries of the singlet and triplet states are not the same. The cationic complex formed by the one-electron oxidation of (η5-C5H5)2Ti(bpy) has been isolated as a hexafluorophosphate salt. The magnetic susceptibility and EPR spectrum of this material are characteristic of a d1 complex.

Original languageEnglish (US)
Pages (from-to)3425-3430
Number of pages6
JournalJournal of the American Chemical Society
Issue number13
StatePublished - Jun 1 1979
Externally publishedYes

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry


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