Paper published as part of the Quantum-Chemical Calculations and their applications special issue.
Molecular orbital analysis of the inverse halogen dependence of nuclear magnetic shielding in LaX3, X = F, Cl, Br, I†
Article first published online: 29 JUN 2010
Copyright © 2010 John Wiley & Sons, Ltd.
Magnetic Resonance in Chemistry
Supplement: Quantum-Chemical Computations of Magnetic Resonance Parameters
Volume 48, Issue S1, pages S76–S85, December 2010
How to Cite
Moncho, S. and Autschbach, J. (2010), Molecular orbital analysis of the inverse halogen dependence of nuclear magnetic shielding in LaX3, X = F, Cl, Br, I. Magn. Reson. Chem., 48: S76–S85. doi: 10.1002/mrc.2632
- Issue published online: 22 NOV 2010
- Article first published online: 29 JUN 2010
- Manuscript Accepted: 18 MAY 2010
- Manuscript Revised: 17 MAY 2010
- Manuscript Received: 30 MAR 2010
- National Science Foundation. Grant Numbers: CHE 447321, 952253
- US Department of Energy
The NMR nuclear shielding tensors for the series LaX3, with X = F, Cl, Br and I, have been computed using two-component relativistic density functional theory based on the zeroth-order regular approximation (ZORA). A detailed analysis of the inverse halogen dependence (IHD) of the La shielding was performed via decomposition of the shielding tensor elements into contributions from localized and delocalized molecular orbitals. Both spin-orbit and paramagnetic shielding terms are important, with the paramagnetic terms being dominant. Major contributions to the IHD can be attributed to the LaX bonding orbitals, as well as to trends associated with the La core and halogen lone pair orbitals, the latter being related to XLa π donation. An ‘orbital rotation’ model for the in-plane π acceptor f orbital of La helps to rationalize the significant magnitude of deshielding associated with the in-plane π donation. The IHD goes along with a large increase in the shielding tensor anisotropy as X becomes heavier, which can be associated with trends for the covalency of the LaX bonds, with a particularly effective transfer of spin-orbit coupling induced spin density from iodine to La in LaI3. Copyright © 2010 John Wiley & Sons, Ltd.