The influence of basis set on the ab initio prediction of internal rotation barrier heights in ethene thiol

In this report the effects of basis set size and electron correlation on the internal rotation barrier heights in ethene thiol are investigated and compared with experimental data. At all levels of theory reasonable agreement is obtained for the barrier tosyn/anti rotation (experimental value: 9.6 kJ/mol), however, theanti barrier (experimental value: 0.14 kJ/mol) is consistently overestimated by approximately a factor of 10. A comparison of ab initio predictions of torsional energy distributions and rotational constant variations as a function of torsional state with the corresponding experimental quantities is presented.     

Aryl-aryl coupling via directed lithiation and oxidation

Aryl lithium reagents formed by directed lithiation reactions undergo transmetallation with copper(I) salts to form organocuprates, which may be efficiently oxidized to yield ortho-substituted biaryls.     

Measurement of the Michel parameter rho in muon decay

The TWIST Collaboration has measured the Michel parameter rho in normal muon decay, mu(+)--> e(+)nu(e)nu (mu). In the standard model, rho = 3/4. Deviations from this value imply mixing of left- and right-handed muon and electron couplings. We find rho=0.750 80+/-0.000 32(stat) +/- 0.000 97(syst) +/- 0.000 23, where the last uncertainty represents the dependence of rho on the Michel parameter eta. This result sets new limits on the W(L)-W(R) mixing angle in left-right symmetric models.     

The heI photoelectron spectra of the halogen azides,XN3(X = Cl and Br) and the halogen isocyanates,XNCO(X = Cl,Br and I)

High yield routes to the unstable halogen azides and isocyanates have permitted vacuum ultraviolet photoelectron spectra to be obtained for the chlorine and bromine azides, and the chlorine, bromine and iodine isocyanates. The results are compared with ab initio and semi-empirical calculations, leading to a reassignment of the photoelectron spectra of the parent acids, HN₃ and HNCO in the high energy region. The halogen azide and isocyanate photoelectron spectra provide an interesting investigation into how the orbitals of a linear pseudohalide grouping are perturbed by an off-azis halogen atom. A photoelectron spectrum for the unknown molecule FNCO is predicted.