Relativistic effects on the 125Te and 33S NMR chemical shifts of various tellurium and sulfur species, together with 77Se of selenium congeners, in the framework of a zeroth-order regular approximation: applicability to tellurium compounds

Abstract

The relativistic effects on absolute magnetic shielding tensors [σ(Z: Z = Te, Se and S)] are explicitly evaluated for various tellurium, selenium and sulfur species using the DFT(BLYP)-GIAO method. Calculations of σ(Te), σ(Se) and σ(S) are performed under the spin–orbit ZORA relativistic (Rlt-so) and nonrelativistic (Non) conditions with the Slater-type basis sets of the quadruple zeta all electron with four polarization functions (QZ4Pae). Structures optimized at the MP2 level under nonrelativistic conditions are employed for the evaluations. While the range of the relativistic effects on the total shielding tensors for Te (Δσ^t(Te)_Rlt-so = σ^t(Te)_Rlt-so − σ^d+p(Te)_Non) is predicted to be −55 to 658 ppm, that for Δσ^t(S) is predicted to be 5 to 32 ppm, except for Me₂SBr₂ (TBP), where Δσ^t(S)_Rlt-so = −29 ppm. The range for Δσ^t(Se) is 2 to 153 ppm. The magnitudes of the relativistic effects on σ^t(Te), σ^t(Se) and σ^t(S) are about 25 : 5 : 1. The applicability of σ^t(Te)_Rlt-so to analyze δ(Te)_obsd is also examined, mainly with the OPBE//OPBE method under the spin–orbit ZORA relativistic conditions with QZ4Pae, in addition to the above method.