HIGH RESOLUTION RAMAN SPECTROSCOPY OF GASES: X. ROTATIONAL SPECTRUM OF BUTATRIENE (H2C=C=C=CH2)

Abstract

The rotational Raman spectrum of butatriene (H2C=C=C=CH2) at a pressure of 2 cm. Hg was photographed with a 21 ft. grating spectrograph. An analysis of this spectrum (based on the symmetric top approximation) yields the rotational constant [Formula: see text](B0 + C0) = 0.13141 ± 0.0001 cm−1. If the two outer C=C bonds in butatriene are assumed to have the same length as the C=C bonds in allene,namely 1.309 Å, it is found that the central C=C bond has a length of 1.284 ± 0.006 Å, a value which is shorter than that of the C=C bonds in ethylene and in allene.