Athanassios Nicolaides

Is the most stable gas-phase isomer of the benzenium cation a face-protonated π-complex?

The recent suggestion, based on gas-phase experimental data, that the most stable isomer of protonated benzene has a face-protonated π-complex structure is not supported by our detailed computations which indicate that the π-complex is a second-order saddle point on the potential energy surface, lying 199 kJ mo–1 higher in energy than the well-established C2vσ-protonated structure.

Determination of the chirality of enantiomeric [16O, 17O, 18O] sulfate esters by IR spectroscopy: an ab initio evaluation

The calculated shifts accompanying oxygen isotopic substitution in the symmetric and antisymmetric >SO2 stretching vibrational frequencies of 2,2-dioxo-1,3,2-dioxothianes confirm the experimental finding that these shifts can serve as a diagnostic tool for the determination of the absolute configuration at the sulfur centre of molecules contaIntng chiral [16O, 17O, 18O] sulfate groups.