Rotational analysis of several bands in the high-resolution infrared spectrum of butadiene-1-13C1: assignment of vibrational fundamentals

Butadiene-1-13C1 was synthesized, and its high-resolution (0.002 cmK1) infrared spectrum was recorded for several bands in the midinfrared region. A complete analysis of the rotational structure in the C-type band at 524.485 cmK1 for CH2 twisting and a partial analysis of the rotational structure in the C-type bands at 900.0 and 909 cmK1 were performed. Of these latter two bands, which are of comparable intensity, the higher frequency one is largely CH2 out-of-plane wagging and the lower frequency one is largely 13CH2 out-of-plane wagging. Taken together these bands correlate with one infrared-active au fundamental and one Raman-active bg fundamental of butadiene. The ground state rotational constants are AZ1.3887919 (6), BZ0.1436683 (3), and CZ0.1302251 (3) cmK1, and upper state rotational constants are reported for the bands at 524.485 and 900.0 cmK1. Medium resolution infrared and Raman spectra gave a complete assignment of the vibrational fundamentals, including 11 fundamentals observed directly for the first time. q 2005 Elsevier B.V. All rights reserved