Chemical-shift tensors of heavy nuclei in network solids: a DFT/ZORA investigation of ²⁰⁷Pb chemical-shift tensors using the bond-valence method

Abstract

Cluster models are used in calculation of (207)Pb NMR magnetic-shielding parameters of α-PbO, β-PbO, Pb3O4, Pb2SnO4, PbF2, PbCl2, PbBr2, PbClOH, PbBrOH, PbIOH, PbSiO3, and Pb3(PO4)2. We examine the effects of cluster size, method of termination of the cluster, charge on the cluster, introduction of exact exchange, and relativistic effects on calculation of magnetic-shielding tensors with density functional theory. Proper termination of the cluster for a network solid, including approximations such as compensation of charge by the bond-valence (BV) method, is essential to provide results that agree with experiment. The inclusion of relativistic effects at the spin-orbit level for such heavy nuclei is an essential factor in achieving agreement with experiment.

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

“…[24][25][26]41 Such calculations provide a strong linear correlation between experimental and calculated magnetic-shielding values. However, with this procedure, the span (Ω) of the shielding tensor is systematically underestimated for hemidirected lead sites, by as much as several hundred ppm.…”

“…However, with this procedure, the span (Ω) of the shielding tensor is systematically underestimated for hemidirected lead sites, by as much as several hundred ppm. 41 For calculations using the scalar relativistic ZORA Hamiltonian, the deviation can be as high as 2000 ppm, a substantial disagreement. 41 In this study, we present calculations of principal components of 207 Pb magnetic-shielding tensors for a variety of different co-ordination environments and different oxidation states.…”

“…41 For calculations using the scalar relativistic ZORA Hamiltonian, the deviation can be as high as 2000 ppm, a substantial disagreement. 41 In this study, we present calculations of principal components of 207 Pb magnetic-shielding tensors for a variety of different co-ordination environments and different oxidation states. A comparison between the calculated principal components at the scalar and spin−orbit levels shows the importance of the spin−orbit terms.…”

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

“…37 When tin is coordinated to lighter atoms, chemical shifts and spin-spin couplings calculated with inclusion of SO coupling and without it are quite similar, suggesting that inclusion of such terms is not significant. 29,31 Comparisons of various theoretical approaches are presented, with or without SO coupling, using the ZORA-DFT methodology. 45 The role of SO coupling on calculated magnetic-shielding tensors is highly system-dependent.…”

Determination of the 31P and 207Pb Chemical Shift Tensors in Pyromorphite, Pb5(PO4)3Cl, by Single‐Crystal NMR Measurements and DFT Calculations

“…The shielding constants σ computed by CASTEP were converted to chemical shifts δ using the empirical relation σ = 8643 ppm -0.869δ. [25] Both error estimate and shielding conversion also apply to Table 4.…”