Combined microwave-optical barrier determination for molecules with a heavy symmetric internal top: CF3NO and CF3CHO
1986; Elsevier BV; Volume: 132; Issue: 2 Linguagem: Inglês
10.1016/0009-2614(86)80088-4
ISSN1873-4448
AutoresDavid W. Knight, A. Peter Cox,
Tópico(s)Atmospheric Ozone and Climate
ResumoThe torsional data for CF3NO have been rein vest igated. A model with a single degree of freedom and three adjustable parameters is sufficient to fit data to v = 8 in the electronic ground state. For CF3NO we obtain Fo = 1.9822(42) cm−1, V3 = 238.4(1.6) cm−1 and V6 = −5.8(1.6) cm−1 or Fo = 1.9894(66) cm−1,F3= −0.194(55) cm−1 and V3 = 239.3(1.9) cm−1. A similar treatment for CF3CHO gives Fo = 1.97(14) cm−1, V3 = 305(25) cm−1 and V6 = −8.7(1.2) cm−1. A need for a re-examination of the torsional fundamental is indicated for CF3CHO. These studies support the general conclusion that for a heavy internal top the internal rotation constant, Fo, required to fit a range of torsional splittings is different from that calculated from structural considerations alone. The difference indicates a large change in F with torsional averaging.
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