Microwave spectroscopic study of the conformations,relative energies,and dipole moments of ethyl cyanoformate |
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Authors: | Richard D Suenram Nancy S True Robert K Bohn |
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Institution: | 1. Department of Chemistry, The University of Connecticut, Storrs, Connecticut 06268 USA;2. Institute of Materials Science, The University of Connecticut, Storrs, Connecticut 06268 USA |
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Abstract: | The microwave spectrum of ethyl cyanoformate displays a-type band spectra from three nearly prolate conformers. High-resolution spectra of the two more stable species have been assigned. One form, designated extended, has rotational constants A″ = 6453.3(4) MHz, B″ = 1500.47(6) MHz, C″ = 1236.36(6) MHz, which are consistent with a syn-anti τ1 (OCOC) = 0°, τ2 (COCC) = 180°] structure. The second form, labeled compact, has rotational constants A″ = 6787.8(7) MHz, B″ = 1549.38(8) MHz, C″ = 1406.80(8) MHz, which are consistent with a syn-gauche τ1 (OCOC) = 0°, τ2 (COCC) ~ 90°] structure. The extended form is marginally more stable, ΔE = 55 ± 27 cm?1. The extended conformer has dipole moment components μa = 4.44(7), μb ~ 0 D and the compact conformer has dipole moment components μa = 4.25(7), μb = 0, μc = 1.08(23) D. The third conformer (relative energy 600 ± 140 cm?1) has the most intense band series even at ?63°C. the bands of this conformer are unresolvable into individual rotational transitions. |
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