Bonding trends across the series of tricarbonato-actinyl anions [(AnO2)(CO3)3]4− (An = U–Cm): the plutonium turn. Issue 8 (3rd February 2017)

• Record Type: Journal Article
• Authors: Liu, Jian-Biao; Chen, Guo P.; Huang, Wei; Clark, David L.; Schwarz, W. H. Eugen; Li, Jun
• Is Part Of: Dalton transactions. Volume 46:Issue 8(2017)
• Page Start: 2542
• Page End: 2550
• Publication Date: 2017-02-03
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c6dt03953g
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : Strong variation of actinide f-orbital energy-levels with nuclear AND ionic charges lowers the highest possible oxidation-states from Pu onwards. Abstract : 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 2 nd coordination sphere affect the equatorial An←Oeq bonds more than the axial AnOax bonds. Common actinide contraction is found for calculated and experimental axial bond lengths of92 U to94 Pu, though no longer for94 Pu to96 Cm. The tendency of U to Pu forming actinyl(vi ) species dwindles away toward Cm, which already features the preferred An III /Ln III oxidation 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 AnOax bonds and reducing the highest possible oxidation states of the later actinides.