VIBRATIONAL OVERTONE SPECTROSCOPY OF GASEOUS FERROCENE, RUTHENOCENE, AND RELATED-COMPOUNDS

The vibrational overtone spectra of ferrocene, acetylferrocene, ruthen ocene, and cyclopentadienyltitanium trichloride have been recorded in the third overtone region of the C-H stretch vibration, 4 nu(C-H). All of the spectra display four peaks in this region. The transition wave numbers and relative intensities of the metallocene spectra are invari ant to changes of the metal (iron, ruthenium, or titanium) or the liga nd (chloride or acetylcyclopentadienyl). The overtone spectrum of gase ous cyclopentadiene in the near infrared and visible regions has been recorded for comparison to the metallocene spectra. The aliphatic, nu( C-H)B, and olefinic, nu(C-H)(0), local mode vibrational progressions w ere identified. The 4 nu(C-H0) in cyclopentadiene occurs at the same w avenumber as the lowest energy peak in the metallocenes. Shoulders on the 4 nu(C-H0) band contour in cyclopentadiene correspond to the metal locene transition wavenumbers. It is argued that the transitions corre sponding to these shoulders were dark in the cyclopentadiene overtone spectrum but became bright in the metal-coordinated ring.