Bonding trends across the series of tricarbonato-actinyl anions [(AnO2)(CO3)3]4-(An = U-Cm): the plutonium turn.
Actinyl-tricarbonato anions [(AnO2)(CO3)3]4-(An = U-Cm) in various environments were investigated using theoretical approaches of quantum-mechanics, molecular-mechanics and cluster-models. Cations and solvent molecules in the 2ndcoordination sphere affect the equatorial An←Oeqbonds more than the axial An[triple bond, length as m-dash]Oaxbonds. Common actinide contraction is found for calculated and experimental axial bond lengths of92U to94Pu, though no longer for94Pu to96Cm. The tendency of U to Pu forming actinyl(vi) species dwindles away toward Cm, which already features the preferred AnIII/LnIIIoxidation state of the later actinides and all lanthanides. The well known change from d-type to typical U-Pu-Cm type and then to f-type behavior is labeled as the plutonium turn, a phenomenon that is caused by f-orbital energy-decrease and f-orbital localization with increase of both nuclear charge and oxidation state, and a non-linear variation of effective f-electron population across the actinide series. Both orbital and configuration mixing and occupation of antibonding 5f type orbitals increase, weakening the AnOaxbonds and reducing the highest possible oxidation states of the later actinides.
College of Chemistry, Chemical Engineering and Materials Science, Collaborative Innovation Center of Functionalized Probes for Chemical Imaging in Universities of Shandong, Shandong Normal University, Jinan 250014, China and Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084, China. junli@tsinghua.edu.cn.
Jian-Biao
JB
Liu
Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084, China. junli@tsinghua.edu.cn.
Guo P
GP
Chen
Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084, China. junli@tsinghua.edu.cn.
Wei
W
Huang
Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
David L
DL
Clark
Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084, China. junli@tsinghua.edu.cn and Physical and Theoretical Chemistry, University of Siegen, 57068, Germany.
W H Eugen
WH
Schwarz
Department of Chemistry and Key Laboratory of Organic Optoelectronics & Molecular Engineering of the Ministry of Education, Tsinghua University, Beijing 100084, China. junli@tsinghua.edu.cn and Environmental Molecular Science Laboratory, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
Jun
http://orcid.org/0000-0002-8456-3980
J
Li