Infrared spectroscopy of jet-cooled transition metal carbonyls.

Rotationally resolved infrared absorption spectra of jet-cooled transition metal carbonyls in the region of CO stretching vibrations near 2000 cm-1 are reported in this thesis. The molecules span spherical, symmetric and asymmetric tops. Theories and their deductions related to the explanation of the various aspects of spectra are simply elucidated. The measurement of the band centres of spectra of M(CO)6 (M=Cr, Mo, W) has an improvement of 103 in precision. The rotational constants determined are very close to those derived from electron diffraction results. Analysis of the spectra of MeMn(CO)5 (Me=CH3, CD3) of two strongly allowed bands yielded values for the band centres and rotational constants for parallel bands of both isotopic species, and for the perpendicular band of CH3Mn(CO)5; the latter also provided an estimate of the Coriolis constant for this vibration. The spectra were consistent with essentially free rotation of the methyl group. The rotational constants were in close agreement with those derived from electron diffraction data; however, the B rotation constants provide a revised estimate for the axial Mn-CO bond length. The parallel band of C5H5Mn(CO)3 is analysed and the band centre and B rotational constant of excited state are estimated. Three bands of C4H6Fe(C0)3, one of which exhibits essentially a-type transitions, the second b-type transitions, and the third a- and c-type transitions, are analysed. The results confirm the effective Cs symmetry of the Fe(C0)3 unit and yield values for the band centres and rotational constants of the upper levels of two of the three bands. The relative intensities of the a and 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. Spectra of C5H5Co(CO)2 are also reported, and band centres of the two bands of CO stretching vibrations are estimated.