Large relativistic effects in 119Sn NMR parameters: a case study of complex anions [Cp*M(SnCl3)nCl3-n]-, where M = Rh, Ir; n = 1, 2, 3

Relativistic effects are found to be important for the estimation of NMR parameters in halogen-bonded complexes, mainly when they involve the heavier elements, iodine and astatine. A detailed study of 60 binary complexes formed between dihalogen molecules (XY with X, Y = F, Cl, Br, I and At) and four Lewis bases (NH3, H2O, PH3 and SH2) was carried out at the MP2/aug-cc-pVTZ/aug-cc-pVTZ-PP computational level to show the extent of these effects. The NMR parameters (shielding and nuclear quadrupolar coupling constants) were computed using the relativistic Hamiltonian ZORA and compared to the values obtained with a non-relativistic Hamiltonian. The results show a mixture of the importance of the relativistic corrections as both the size of the halogen atom and the proximity of this atom to the basic site of the Lewis base increase.

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ChemInform Abstract:119Sn NMR Parameters

Chemischer Informationsdienst ◽

10.1002/chin.198630364 ◽

1986 ◽

Vol 17 (30) ◽

Author(s):

B. WRACKMEYER

Keyword(s):

Nmr Parameters ◽

119Sn Nmr

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Strategies for extracting NMR parameters from MAS, DOR and MQMAS spectra. A case study for Na4P2O7

Solid State Nuclear Magnetic Resonance ◽

10.1016/s0926-2040(99)00054-5 ◽

1999 ◽

Vol 15 (3) ◽

pp. 171-180 ◽

Cited By ~ 39

Author(s):

G. Engelhardt ◽

A.P.M. Kentgens ◽

H. Koller ◽

A. Samoson

Keyword(s):

Nmr Parameters

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Inclusion of Relativistic Effects in Electronic Structure Calculations

Australian Journal of Physics ◽

10.1071/ph860667 ◽

1986 ◽

Vol 39 (5) ◽

pp. 667 ◽

Cited By ~ 2

Author(s):

KG Dyall

Keyword(s):

Molecular Structure ◽

Electronic Structure ◽

Dirac Equation ◽

Atomic Number ◽

Perturbation Methods ◽

Relativistic Effects ◽

Electronic Structure Calculations ◽

Variational Treatment ◽

Structure Calculations

The effects of relativity on atomic and molecular structure are discussed with an indication of their importance as a function of atomic number. Perturbation methods for the inclusion of relativistic effects are briefly analysed in terms of the Dirac equation; the multi-configuration Dirac-Fock method for the variational treatment of relativistic effects is then discussed in more detail. Finally, a case study on 2p ionisation in Ca is presented, in which higher-order relativistic effects are important.

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[Pt@Pb12]2– — A challenging system for relativistic density functional theory calculations of 195Pt and 207Pb NMR parameters

Canadian Journal of Chemistry ◽

10.1139/v11-054 ◽

2011 ◽

Vol 89 (7) ◽

pp. 814-821 ◽

Cited By ~ 7

Author(s):

Boris Le Guennic ◽

Jochen Autschbach

Keyword(s):

Density Functional ◽

Chemical Shifts ◽

Relativistic Effects ◽

Magnetic Coupling ◽

Principal Component ◽

Density Functional Theory Calculations ◽

Coupling Constants ◽

Spin Coupling ◽

Test Case ◽

Nmr Parameters

We report computations of NMR chemical shifts and indirect spin-spin coupling constants (J couplings) for the [Pt@Pb12]2– “superatom”. The system is strongly influenced by relativistic effects. The Pt–Pb coupling constant is predicted to be negative, with its magnitude being in reasonable agreement with experiment. Pt and Pb chemical shifts also agree reasonably well with experiment. The Pb shielding tensor is strongly anisotropic, with a large deshielding principal component dominated by magnetic coupling between frontier orbitals of the cluster that resemble atomic g orbitals. The NMR parameters are sensitive to approximations made in the computations and require the inclusion of spin-orbit coupling in the theoretical model to achieve reliable results. Computing the NMR parameters of the compact [Pt@Pb12]2– system with its many electrons proves to be a challenging test case for relativistic density functional methods.

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