Temperature Dependence of ¹ H Paramagnetic Chemical Shifts in Actinide Complexes, Beyond Bleaney's Theory: The An ^VI O ₂ ²⁺ –Dipicolinic Acid Complexes (An=Np, Pu) as an Example

Actinide +VI complexes ( = , and ) with dipicolinic acid derivatives were synthesized characterized by powder XRD, SQUID magnetometry NMR spectroscopy. In addition, described first principles CAS based two-component spin-restricted DFT methods. The analysis of the 1H paramagnetic chemical shifts for all protons ligands according to X-rays structures shows that Fermi contact contribution is negligible in agreement spin density determined unrestricted DFT. magnetic susceptibility tensor combining SQUID, pNMR Evans’ method. SO-RASPT2 results fit well experimental shifts. role counterions solid phase pointed out; their presence impacts properties complex. temperature dependence has a strong contribution, contrarily Bleaney's theory lanthanide complexes. fitting two-Kramers-doublet model complex non-Kramers-doublet allows evaluation energy gaps moments center.