In:
Helvetica Chimica Acta, Wiley, Vol. 86, No. 12 ( 2003-12), p. 4048-4060
Abstract:
We present calculations on the parity‐conserving and the parity‐violating potentials in several MeOH isotopomers for the torsional motion by the newly developed methods of electroweak quantum chemistry from our group. The absolute magnitudes of the parity‐violating potentials for MeOH are small compared to H 2 O 2 and C 2 H 4 , but similar to C 2 H 6 , which is explained by the high (threefold) symmetry of the torsional top in MeOH and C 2 H 6 . ‘Chiral’ and ‘achiral’ isotopic substitutions in MeOH lead to small changes only, but vibrational averaging is discussed to be important in all these cases. Simple isotopic sum rules are derived to explain and predict the relationships between parity‐violating potentials in various conformations and configurations of the several isotopomers investigated. The parity‐violating energy difference Δ pv E = E pv ( R )− E pv ( S ) between the enantiomers of chiral CHDTOH, first synthesized by Arigoni and co‐workers, is for two conformers ca. −3.66⋅10 −17 and for the third one +7.32⋅10 −17 hc cm −1 . Thus, for Δ pv E , the conformation is more important than the configuration (at the equilibrium geometries, without vibrational averaging). Averaging over torsional tunneling may lead to further cancellation and even smaller values.
Type of Medium:
Online Resource
ISSN:
0018-019X
,
1522-2675
DOI:
10.1002/hlca.200390336
Language:
English
Publisher:
Wiley
Publication Date:
2003
detail.hit.zdb_id:
74-7
detail.hit.zdb_id:
1475013-2
