ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The far infrared spectrum of gaseous 2-fluoropropenoyl fluoride CH2CFCFO, has been recorded at a resolution of 0.10 cm−1 in the 350–35 cm−1 region. The asymmetric torsional fundamental of the more stable s-trans (two double bonds oriented trans to one another) and the high energy s-cis conformations have been observed at 84.1 and 68.5 cm−1, respectively, each with excited states falling to lower frequencies. From these data, the asymmetric torsional potential function governing internal rotation about the C–C bond has been determined. The potential coefficients are V1=−201±4, V2=2106±16, V3=382±6, V4=−41±5, and V5=−74±3 cm−1. The s-trans to s-cis and s-cis to s-trans barriers have been determined to be 2232 and 2124 cm−1, respectively, with an enthalpy difference between the conformations of 108±26 cm−1 (309±74 cal/mol). From variable temperature studies of the Raman spectrum, the conformational enthalpy difference has been determined to be 187±39 cm−1 (535±112 cal/mol) and 370±82 cm−1 (1058±234 cal/mol) for the gas and liquid, respectively. A complete assignment of the vibrational fundamentals observed from the infrared (3500–50 cm−1) spectra of the gas and solid and the Raman (3200–10 cm−1) spectra of all three physical states is proposed. All of these data are compared to the corresponding quantities obtained from ab initio Hartree–Fock gradient calculations employing both the 3-21G and 6-31G* basis sets. Additionally, complete equilibrium geometries have been determined for both rotamers. The results are discussed and compared with the corresponding quantities obtained for some similar molecules.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.457259
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