INFRARED-LASER SPECTROSCOPY OF JET-COOLED BUTADIENE IRON TRICARBONYL

Rotationally resolved infrared absorption spectra of jet-cooled butadi ene iron tricarbonyl in the region of the three strongly allowed CO-st retching vibrations near 2000 cm(-1) have been measured by use of diod e lasers. The observation of three bands, one of which exhibits essent ially a-type transitions, the second b-type transitions, and the third a- and c-type transitions, confirms the effective C-s symmetry of the Fe(CO)(3) unit in the molecule. Analysis of the spectra yields values for the band centers and for the rotational constants of the upper le vels of two of the three bands. The relative intensities of the a and the c components of the hybrid band provide an estimate of 1:4 for the ratio of the square of the transition moments of this vibration.