Quasi-relativistic study of nuclear electric quadrupole coupling constants in chiral molecules containing heavy elements

Abstract

A quasi-relativistic (two-component) zeroth-order regular approximation model potential approach is employed to calculate nuclear electric quadrupole coupling tensors of the chiral polyhalomethane derivatives CHBrClF and CHClFI. Each of these two chiral compounds contains two nuclei with electric quadrupole moments, which poses special challenges for an analysis of high-resolution rovibrational spectra and, thus, renders predictions of electric field gradients and resulting nuclear electric quadrupole coupling tensors in such molecules particularly valuable. The theoretical approach is studied with respect to the influence of relativistic effects, by comparison to scalar-relativistic and non-relativistic calculations, and electron correlation effects, which are included within different flavours of density functional theory. The quality of the calculations is assessed by comparison to results from experiments reported previously by Bauder et al. and Soulard et al., respectively. It is shown that the local density approximation exchange-correlation functional gives results that agree with experiment within 12 % for all nuclear quadrupole coupling tensor components of 79Br and 127I. This benchmark test of the quasi-relativistic approach indicates its applicability to support upcoming microwave experiments with chiral heavy-element containing main group compounds.