Issue 34, 2016

Toward an absolute NMR shielding scale using the spin-rotation tensor within a relativistic framework

Abstract

One of the most influential articles showing the best way to get the absolute values of NMR magnetic shieldings, σ (non-measurables) from both accurate measurements and theoretical calculations, was published a long time ago by Flygare. His model was shown to break down when heavy atoms are involved. This fact motivated the development of new theories of nuclear spin-rotation (SR) tensors, which consider electronic relativistic effects. One was published recently by some of us. In this article we take another step further and propose three different models that generalize Flygare's model. All of them are written using four-component relativistic expressions, though the two-component relativistic SO-S term also appears in one. The first clues for these developments were built from the relationship among σ and the SR tensors within the two-component relativistic LRESC model. Besides, we had to introduce a few other well defined assumptions: (i) relativistic corrections must be included in a way to best reproduce the relationship among the (e–e) term (called “paramagnetic” within the non-relativistic domain) of σ and its equivalent part of the SR tensor, (ii) as happens in Flygare's rule, the shielding of free atoms shall be included to improve accuracy. In the highest accurate model, a new term known as Spin–orbit due to spin, SO-S (in this mechanism the spin-Zeeman Hamiltonian replaces the orbital-Zeeman Hamiltonian), is included. We show the results of the application of those models to halogen containing linear molecules.

Graphical abstract: Toward an absolute NMR shielding scale using the spin-rotation tensor within a relativistic framework

Article information

Article type
Paper
Submitted
14 Jan 2016
Accepted
18 Jul 2016
First published
19 Jul 2016

Phys. Chem. Chem. Phys., 2016,18, 23572-23586

Toward an absolute NMR shielding scale using the spin-rotation tensor within a relativistic framework

I. A. Aucar, S. S. Gomez, C. G. Giribet and G. A. Aucar, Phys. Chem. Chem. Phys., 2016, 18, 23572 DOI: 10.1039/C6CP03355E

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements