Microwave rotational spectra were measured for eight isotopomers of ?5-C5H5Cr(CO)2NO using a pulsed-beam, Fourier transform spectrometer. The normal isotopomer is a near-symmetric rotor with A = 1001.693(2), B = 797.2724(6), and C = 797.0143(6) MHz. This complex has a “piano-stool” type structure, with one symmetry plane. The accidental, near-symmetric top inertia tensor gives a clear indication of different bonding and structural parameters for the nitrosyl group and the carbonyl groups, since 3-fold symmetry for the nitrosyl and carbonyl groups would result in a much larger value for B - C. The nitrosyl and carbonyl groups form different angles with the z-axis which passes through the Cr atom and center of C5H5. The C5H5-Cr-NO angle is 128°, and the C5H5-G-CO angle is 120°. The distance from the Cr atom to the C5H5 ring is z (Cr-C5H5) = 1.86 Å. The a-axis forms an angle of 4° with the z-axis. Other structural parameters are obtained and discussed. The C5H5 ring is oriented so that two of the cyclopentadienyl carbon atoms are staggered with respect to the NO nitrogen atom. The 14N quadrupole coupling values are eQqaa = 0.312(2) and eQqbb = −0.448(2) MHz.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry