Calculating NMR Chemical Shifts for Paramagnetic Metal Complexes from First-Principles.
Paramagnetic effects on NMR shifts (pNMR) for paramagnetic metal complexes are calculated from first-principles, without recourse to spin Hamiltonian parameters. A newly developed code based on complete active space (CAS) and restricted active space (RAS) techniques in conjunction with treating spin-orbit (SO) coupling via state interaction is applied to (13)C NMR shifts of actinyl tris-carbonate complexes, specifically [UO2(CO3)3](5-) and [NpO2(CO3)3](4-). The experimental pNMR shifts as well as the sizable difference of the (13)C NMR shift for these iso-electronic species are well reproduced by the calculations. Approximations to the pNMR shift equations using spin Hamiltonian parameters or the magnetic susceptibility are calculated for the same systems at the same level of theory, and it is shown how the approximations relate to the ab initio data.
Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, United States.
Frédéric
F
Gendron
Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, United States.
Kamal
K
Sharkas
Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000, United States.
Jochen
J
Autschbach
NMR shift; ab initio theory; actinide complexes; hyperfine coupling; paramagnetism; relativistic effects