The characterization and the understanding of the magnetic properties of open-shell actinide complexes are of great importance both experimentally and theoretically. Due to their partially filled 5f shell, actinide complexes exhibit interesting magnetic properties which can be particularly difficult to rationalize without the help of quantum chemistry. These systems are also very challenging for quantum chemistry due to (i) their relative large number of low-lying electronic states, (ii) the comparable magnitude of the spin-orbit coupling and the crystal-field interaction and (iii) the strong electronic correlation. This presentation is focused on calculations of the ligand paramagnetic NMR (pNMR) chemical shifts in a series of actinyl-carbonate complexes AnO2(CO3)3q- (An = U, Np and Pu) and in the organometallic complex UCp3CH3. The use of multireferential approaches (CASSCF and RASSCF) including spin-orbit coupling allowed to properly reproduce the experimental 13C and 1H pNMR shifts. The results will be analyzed with the help of the natural spin orbitals generated from the SO wave functions, revealing the complex balance between the spin-delocalization and spin-polarization mechanisms which take place at the nucleus of interest in order to generate the magnetization, and hence the pNMR shifts.

Multi-reference calculations of NMR shifts in open-shell actinide complexes

254th National Meeting (2017)

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