Pentavalent Curium, Berkelium, and Californium in Nitrate Complexes: Extending Actinide Chemistry and Oxidation States.
- Author(s): Kovács, Attila;
- Dau, Phuong D;
- Marçalo, Joaquim;
- Gibson, John K
- et al.
Published Web Locationhttps://doi.org/10.1021/acs.inorgchem.8b01450
Pentavalent actinyl nitrate complexes AnVO2(NO3)2- were produced by elimination of two NO2 from AnIII(NO3)4- for An = Pu, Am, Cm, Bk, and Cf. Density functional theory (B3LYP) and relativistic multireference (CASPT2) calculations confirmed the AnO2(NO3)2- as AnVO2+ actinyl moieties coordinated by nitrates. Computations of alternative AnIIIO2(NO3)2- and AnIVO2(NO3)2- revealed significantly higher energies. Previous computations for bare AnO2+ indicated AnVO2+ for An = Pu, Am, Cf, and Bk, but CmIIIO2+: electron donation from nitrate ligands has here stabilized the first CmV complex, CmVO2(NO3)2-. Structural parameters and bonding analyses indicate increasing An-NO3 bond covalency from Pu to Cf, in accordance with principles for actinide separations. Atomic ionization energies effectively predict relative stabilities of oxidation states; more reliable energies are needed for the actinides.