Oxalyl halides . Analysis of the 3480 Å absorption system of oxalyl chloridefluoride</SBT>

Oxalyl chloridefluoride (COCl)(COF) exhibits moderately strong discrete absorption in the 3050-3540Å region. The band spectrum has been analyzed as an allowed electronic transition of the planar trans molecule. The most active vibrations are the carbonyl stretching modes ν₁' and ν₂' and the in-plane bending mode ν₉. Various other fundamental frequencies in the combining electronic states have been identified. The 0 ₀⁰ band is at 28 724.5 cm ^-1; partial rotational analysis confirms that this band is type C. The appearance of "line" structure in the wings of the band is discussed and an explanation offered. The vibrational and rotational analyses confirm that the transition is ùA″- X∼¹A' under the C_s point group, as expected for a singlet-singlet n → π ^∗ type of excitation.