DFT Study of Oxo-Functionalized Pentavalent Dioxouranium Complexes: Structure, Bonding, Ligand Exchange, Dimerization, and U(V)/U(IV) Reduction of OUOH and OUOSiH<sub>3</sub> Complexes
Bibliographic record
Abstract
The structural and electronic properties of model oxo-functionalized pentavalent dioxouranium complexes have been studied using scalar relativistic density functional theory (DFT) calculations. The electronic structures of these complexes are compared to those of their hexavalent and pentavalent counterparts with free axial oxo groups while paying particular emphasis on the effect of oxo-functionalization on the formation of binuclear complexes, the U(V)/U(IV) redox potentials, as well as ligand exchange between the axial and equatorial regions of the dioxouranium moiety. The stabilization of the σ(d) orbitals of the UO(2) moiety is one of the major effects of oxo-functionalization. The origin of this effect is the mixing of the σ(d) orbital of the uranyl group with the σ(OH)/σ(OSiH(3)) orbitals of the axial OH/OSiH(3) group. The 6p atomic orbitals of the uranium center are mixed to a greater extent with the σ(d) orbital after stabilization caused by oxo-functionalization. The asymmetric nature of the oxo-functionalization has dramatic effects not only on the U-O bond lengths (elongation by up to 0.24 Å) and U-O bond orders (loss of a full bond order) but also on the formation and type of U(2)O(4) core found in binuclear complexes. The loss of a full bond order upon oxo-functionalization means the axial U-OH/U-OSiH(3) bonds are only slightly stronger than they would be if they were found in the equatorial region of the uranyl moiety. This raises the possibility of ligand exchange between the axial and equatorial regions as well as increasing the stability of the binuclear complexes with butterfly-shaped U(2)O(4) cores relative to those with diamond U(2)O(4) cores. Reductive oxo-functionalization results in complexes with lower electron density at their U(V) centers in comparison to UO(2)(+) complexes. This has dramatic effects on the calculated U(V)/U(IV) redox potentials.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".