TY - JOUR

T1 - On the Geometry Dependence of the NMR Chemical Shift of Mercury in Thiolate Complexes

T2 - A Relativistic DFT Study

AU - Wu, Haide

AU - Hemmingsen, Lars Bo Stegeager

AU - Sauer, Stephan P. A.

PY - 2024

Y1 - 2024

N2 - Thiolate containing mercury(II) complexes of the general formula [Hg(SR)n]2−n have been of great interest since the toxicity of mercury was recognized. 199Hg nuclear magnetic resonance spectroscopy (NMR) is a powerful tool for characterization of mercury complexes. In this work, the Hg shielding constants in a series of [Hg(SR)n]2−n complexes are therefore investigated computationally with particular emphasis on their geometry dependence. Geometry optimizations and NMR chemical shift calculations are performed at the density functional theory (DFT) level with both the zeroth-order regular approximation (ZORA) and four-component relativistic methods. The four exchange-correlation (XC) functionals PBE0, PBE, B3LYP and BLYP are used in combination with either Dyall’s Gaussian-type (GTO) or Slater-type orbitals (STOs) basis sets. Comparing ZORA and four-component calculations, one observes that the calculated shielding constants for a given molecular geometry have a constant difference of ∼1070 ppm. This confirms that ZORA is an acceptable relativistic method to compute NMR chemical shifts. The combinations of 4-component/PBE0/v3z and ZORA/PBE0/QZ4P are applied to explore the geometry dependence of the isotropic shielding. For a given coordination number the distance between mercury and sulfur is the key factor affecting the shielding constant, while changes in bond and dihedral angles and even different side groups have relatively little impact.

AB - Thiolate containing mercury(II) complexes of the general formula [Hg(SR)n]2−n have been of great interest since the toxicity of mercury was recognized. 199Hg nuclear magnetic resonance spectroscopy (NMR) is a powerful tool for characterization of mercury complexes. In this work, the Hg shielding constants in a series of [Hg(SR)n]2−n complexes are therefore investigated computationally with particular emphasis on their geometry dependence. Geometry optimizations and NMR chemical shift calculations are performed at the density functional theory (DFT) level with both the zeroth-order regular approximation (ZORA) and four-component relativistic methods. The four exchange-correlation (XC) functionals PBE0, PBE, B3LYP and BLYP are used in combination with either Dyall’s Gaussian-type (GTO) or Slater-type orbitals (STOs) basis sets. Comparing ZORA and four-component calculations, one observes that the calculated shielding constants for a given molecular geometry have a constant difference of ∼1070 ppm. This confirms that ZORA is an acceptable relativistic method to compute NMR chemical shifts. The combinations of 4-component/PBE0/v3z and ZORA/PBE0/QZ4P are applied to explore the geometry dependence of the isotropic shielding. For a given coordination number the distance between mercury and sulfur is the key factor affecting the shielding constant, while changes in bond and dihedral angles and even different side groups have relatively little impact.

KW - Faculty of Science

KW - NMR

KW - mercury

KW - ZORA

KW - Relativistic Effects

KW - 4-Component Calculations

KW - Density Functional Theory

U2 - 10.48550/arXiv.2312.13120

DO - 10.48550/arXiv.2312.13120

M3 - Journal article

C2 - 38773942

VL - 62

SP - 648

EP - 669

JO - Magnetic Resonance in Chemistry

JF - Magnetic Resonance in Chemistry

SN - 0749-1581

IS - 9

ER -