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

Rotational constants for butadiene and butadiene-2,3-d2 are derived from the analysis of the rotational structure of bands in the highresolution infrared (IR) spectra. Corresponding moments of inertia computed from three quantum chemical calculations agree acceptably with the experimental values. Evidence is growing that the CyC bond lengthens some and the C–C bond shortens some in support of partial p-electron delocalization in butadiene. Refinements are made in the assignment of vibrational fundamentals of butadiene and butadiene-2,3-d2 from new observations of IR and Raman spectra of these species. q 2004 Elsevier B.V. All rights reserved