Vibronic spectroscopy of unsaturated transition metal complexes: CrC2H, CrCH3, and NiCH3.
Vibronically resolved resonant two-photon ionization and dispersed fluorescence spectra of the organometallic radicals CrC(2)H, CrCH(3), and NiCH(3) are reported in the visible and near-infrared wavelength regions. For CrC(2)H, a complicated vibronic spectrum is found in the 11 100-13 300 cm(-1) region, with a prominent vibrational progression having omega(e) (')=426.52+/-0.84 cm(-1), omega(e) (')x(e) (')=0.74+/-0.13 cm(-1). Dispersed fluorescence reveals a v(")=1 level of the ground state with DeltaG(1/2) (")=470+/-20 cm(-1). These vibrational frequencies undoubtedly pertain to the Cr-C(2)H stretching mode. It is suggested that the spectrum corresponds to the A (6)Sigma(+)<--X (6)Sigma(+) band system, with the CrC(2)H molecule being linear in both the ground and the excited state. The related CrCH(3) molecule displays a vibronic spectrum in the 11 500-14 000 cm(-1) region. The upper state of this system displays six sub-bands that are too closely spaced to be vibrational structure, but too widely separated to be K structure. It is suggested that the observed spectrum is a (6)E<--X (6)A(1) band system, analogous to the well-known B (6)Pi<--X (6)Sigma(+) band systems of CrF and CrCl. The ground state Cr-CH(3) vibration is characterized by omega(e) (")=525+/-17 cm(-1) and omega(e) (")x(e) (")=7.9+/-6 cm(-1). The spectrum of NiCH(3) lies in the 16 100-17 400 cm(-1) range and has omega(e) (')=455.3+/-0.1 cm(-1) and omega(e) (')x(e) (')=6.60+/-0.03 cm(-1). Dispersed fluorescence studies provide ground state vibrational constants of omega(e) (")=565.8+/-1.6 cm(-1) and omega(e) (")x(e) (")=1.7+/-3.0 cm(-1). Again, these values correspond to the Ni-CH(3) stretching motion. (c) 2004 American Institute of Physics.
Brugh
Dale J
DJ
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112, USA.
Dabell
Ryan S
RS
Morse
Michael D
MD