Why UO/sub 2//sup 2 +/ is linear and isoelectronic ThO/sub 2/ is bent

Journal Article · Wed Oct 07 04:00:00 EDT 1981 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00410a011· OSTI ID:5806984

Wadt, W R

The isoelectronic species UO/sub 2//sup 2 +/ and ThO/sub 2/ possess very different geometries, namely, UO/sub 2//sup 2 +/ is linear while ThO/sub 2/ is strongly bent (theta/sub exptl/ = 122 +- 2/sup 0/). Relativistic effective core potential (RECP) calculations using Hartree-Fock wave functions and double-zeta-plus-polarization quality basis sets were performed to determine the origin of this difference. The RECP calculations correctly predict the linear and bent geometries of UO/sub 2//sup 2 +/ and ThO/sub 2/ (theta/calcd/ = 118/sup 0/). The Th-O bond length, which is not known experimentally, is calculated to be 1.91 A. Analysis of the results shows that the difference in geometries for UO/sub 2//sup 2 +/ and ThO/sub 2/ has its origin in the relative ordering of the 5f and 6d levels. For uranium the 5f levels are lower and dominathe te back-bonding from the oxygen in UO/sub 2//sup 2 +/, while for thorium the 6d levels are lower and dominate the back-bonding in ThO/sub 2/. Finally, the 5f levels prefer linear geometries, while the 6d prefer bent geometries, hence, the difference between UO/sub 2//sup 2 +/ and ThO/sub 2/. The relative ordering of the 5f and 6d levels has a profound effect.

• Research Organization: Los Alamos National Lab., NM
• OSTI ID: 5806984
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 103:20; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

38 RADIATION CHEMISTRY, RADIOCHEMISTRY, AND NUCLEAR CHEMISTRY
400702* -- Radiochemistry & Nuclear Chemistry-- Properties of Radioactive Materials
ACTINIDE COMPOUNDS
CATIONS
CHALCOGENIDES
CHARGED PARTICLES
COMPARATIVE EVALUATIONS
CONFIGURATION
DATA
ELECTRONIC STRUCTURE
HARTREE-FOCK METHOD
INFORMATION
IONS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
THEORETICAL DATA
THORIUM COMPOUNDS
THORIUM OXIDES
URANIUM COMPOUNDS
URANYL COMPOUNDS