Uranium(IV) Alkyl Complexes of a Rigid Dianionic NON-Donor Ligand: Synthesis and Quantitative Alkyl Exchange Reactions with Alkyllithium Reagents
Bibliographic record
Abstract
Reaction of [(XA 2 )UCl 3 {K(dme) 3 }] (XA 2 = 4,5-bis(2,6-diisopropylanilino)-2,7-di- tert -butyl-9,9-dimethylxanthene) with 2 equiv of ((trimethylsilyl)methyl)lithium or neopentyllithium afforded red-orange [(XA 2 )U(CH 2 SiMe 3 ) 2 ] ( 1 ) and dark red [(XA 2 )U(CH 2 CMe 3 ) 2 ] ( 2 ), respectively. Reaction of 1 with an additional 1 equiv of LiCH 2 SiMe 3 in THF yielded yellow [Li(THF) x ][(XA 2 )U(CH 2 SiMe 3 ) 3 ] ( 3 ), and reaction of [(XA 2 )UCl 3 {K(dme) 3 }] with 3 equiv of methyllithium in dme afforded yellow [Li(dme) 3 ][(XA 2 )UMe 3 ] ( 4 ). Reaction of 1 with 2.1 equiv of LiCH 2 CMe 3 in benzene resulted in rapid conversion to 2, with release of 2 equiv of LiCH 2 SiMe 3 . Similarly, reaction of 1 with 3.3 equiv of MeLi in THF provided 4 as the [Li(THF) x ] + salt, accompanied by 2 equiv of LiCH 2 SiMe 3 . These unusual alkyl exchange reactions resemble salt metathesis reactions, but with elimination of an alkyllithium instead of a lithium halide. Addition of a large excess of LiCH 2 SiMe 3 to 2 or 4 did not generate detectable amounts of 1 by NMR spectroscopy, suggesting that the equilibrium in these reactions lies far to the side of complexes 2 and 4 . In contrast, the reaction of [(XA 2 )Th(CH 2 SiMe 3 ) 2 ] ( 1-Th ) with 2.2 equiv of LiCH 2 CMe 3 yielded an approximate 1:1:3:1 mixture of [(XA 2 )Th(CH 2 CMe 3 ) 2 ] ( 2-Th ), [(XA 2 )Th(CH 2 SiMe 3 )(CH 2 CMe 3 )] ( 5-Th ), LiCH 2 SiMe 3, and LiCH 2 CMe 3 .
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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 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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".