Fully relativistic calculation of nuclear magnetic shieldings and indirect nuclear spin-spin couplings in group-15 and -16 hydrides

Abstract

Fully relativistic calculations of the isotropic and anisotropic parts of both indirect nuclear spin–spin couplings J1(X-H) and J2(H-H) and nuclear magnetic shieldings σ(X) and σ(H) for the group-15 and -16 hydrides are presented. Relativistic calculations were performed with Dirac–Fock wave functions and the random phase approximation method. Results are compared to its nonrelativistic counterpart. Paramagnetic and diamagnetic contributions to the nuclear magnetic shielding constants are also reported. We found very large relativistic corrections to both properties in the sixth-row hydrides (BiH3 and PoH2). Our calculations of the relativistic corrections to the isotropic part of σ at the heavy nucleus X show that it is roughly proportional to Z3.2 in both series of molecules. Paramagnetic term σp is more sensitive to the effects of relativity than the diamagnetic one σd, even though both have a behavior proportional to third power of the nuclear charge Z.

Relativistic Calculations of Spin–Spin Coupling Constants of Heavy Nuclei

“…[28] the group-15 hydrides were also studied by four-component HF theory, and similar trends were obtained. The nuclear shielding tensors were also calculated.…”

“…[14][15][16][17][18][19] Refs. [20][21][22][23][24][25][26][27][28] a) Two-component relativistic generalization of the respective operator.…”

“…More recently, four-component formalisms for the computation of spin-spin coupling constants have been discussed in detail in the framework of molecular electronic structure theory [23], and HF-Dirac applications to small molecules have been reported [24][25][26]28]. These data provide valuable benchmarks for the magnitude of relativistic effects on spin-spin coupling constants, and for alternative implementations or more accurate ab initio computations which can be expected in the future.…”

Structural trends of 77Se1H spin–spin coupling constants and conformational behavior of 2‐substituted selenophenes

“…[28] Relativistic and electron correlation effects are, however, not additive, [29] and calculations of spin-spin coupling constants at the uncorrelated HF-SCF level are often qualitatively wrong. The predictive power of the recent Dirac-Hartree-Fock calculation of the one-bond Se-H coupling in H 2 Se [30] is therefore uncertain. Alternatively, one can include relativistic effects also via perturbation theory or twocomponent approaches.…”

Relativistic calculation of indirect NMR spin-spin couplings using the Douglas-Kroll-Hess approximation

“…Several approaches can be found in the literature incorporating relativistic effects in the calculation of NMR parameters. [8][9][10][11][12][13][14][15] Most of these works are focused on NMSs, while those reporting calculations of SSCs are less abundant. Full fourcomponent calculations were carried out by Visscher et al in the hydrogen halides HX ͑X = F, Cl, Br, and I͒ 13 and by Enevoldsen et al in the tetrahydrides series XH 4 ͑X = C, Si, Ge, Sn, and Pb͒ 9 using the Dirac-Hartree-Fock ͑DHF͒ formalism.…”