Effect of Co-Ordination Chemistry and Oxidation State on the ²⁰⁷Pb Magnetic-Shielding Tensor: A DFT/ZORA Investigation

Abstract

The magnetic shielding tensor of (207)Pb is calculated for various solids exhibiting (1) a holodirected lead(II) center containing a stereochemically inactive lone pair, (2) a hemidirected lead(II) center with a stereochemically active lone-pair, or (3) a lead(IV) center. Tensors investigated at the scalar relativistic level are compared with those calculated with the full ZORA/spin-orbit Hamiltonian. The effect of using GGA density functionals is compared to the use of hybrid density functionals.

Spin–orbit effects on the 119Sn magnetic-shielding tensor in solids: a ZORA/DFT investigation

“…5,6,13 In contrast, tin(IV) species generally exhibit holodirected co-ordination chemistry 11,14,15 with spans under 400 ppm. 16 A similar result is expected for 119 Sn. A recent computational study of 207 Pb NMR parameters illustrates the differences among NMR parameters of lead nuclei at sites of different stereochemistry and how these differences are enhanced by relativistic effects, particularly by spin-orbit (SO) coupling.…”

“…It is evident that SO effects on magnetic-shielding tensors exhibit a strong dependence on the oxidation state of tin. 16 In the case of 207 Pb-containing solids, SO effects show a similar dependence on the oxidation state (+2 or +4) and co-ordination geometry (hemidirected or holodirected) around the 207 Pb nuclei. The results in Fig.…”

“…16 Therefore, we have investigated the performance of the PBE0 functional (with 25% HF exchange), using cluster models and the ZORA/ SO Hamiltonian. A recent study of 207 Pb-containing solids indicates that the inclusion of Hartree-Fock (HF) exchange via hybrid functionals can have significant effects on calculated principal components of the magnetic-shielding tensor.…”

“…The results in Fig. 16 The accuracy of calculated 119 Sn NMR parameters has been systematically investigated for a series of isolated tin(IV) molecules by Bagno et al, 37 using the ZORA/SC and ZORA/SO methods. 16 In the case of 207 Pb-containing solids, SO effects show a similar dependence on the oxidation state (+2 or +4) and co-ordination geometry (hemidirected or holodirected) around the 207 Pb nuclei.…”

“…They have shown that inclusion of SO coupling is important when other heavy atoms such as bromine or iodine are directly bonded to tin. 16 In this study, we present calculations of the principal components of 119 Sn magneticshielding tensors for tin sites with different oxidation states and different co-ordination environments. 37 Predicted isotropic 119 Sn chemical shifts in tin-containing solids calculated with plane-wave DFT techniques employing relativistic pseudopotentials at the ZORA level (without the SO component) are in good agreement with isotropic chemical shifts, although the calculated values do deviate by up to 200 ppm from experiment in some cases.…”