Analysis of the rotational structure in bands in the high-resolution infrared spectra of butadiene and butadiene-2,3- d2: refinement in assignments of fundamentals

Abstract

Rotational constants for butadiene and butadiene-2,3- d 2 are derived from the analysis of the rotational structure of bands in the high-resolution infrared (IR) spectra. Corresponding moments of inertia computed from three quantum chemical calculations agree acceptably with the experimental values. Evidence is growing that the CC bond lengthens some and the C–C bond shortens some in support of partial π-electron delocalization in butadiene. Refinements are made in the assignment of vibrational fundamentals of butadiene and butadiene-2,3- d 2 from new observations of IR and Raman spectra of these species.