Temperature Dependence of H Paramagnetic Chemical Shifts in Actinide Complexes, Beyond Bleaney's Theory: The An O -Dipicolinic Acid Complexes (An=Np, Pu) as an Example.

Actinide +VI complexes ( = , and ) with dipicolinic acid derivatives were synthesized and characterized by powder XRD, SQUID magnetometry and NMR spectroscopy. In addition, and complexes were described by first principles CAS based and two-component spin-restricted DFT methods. The analysis of the H paramagnetic NMR chemical shifts for all protons of the ligands according to the X-rays structures shows that the Fermi contact contribution is negligible in agreement with spin density determined by unrestricted DFT.