Ligand Metalation in the Reactivity of a Tetravalent Uranium Amides
Bibliographic record
Abstract
The reactions of organolithium reagents with the tetravalent UCl(2)[N(SiMe(3))(2)](2) and its DME solvate have been examined. Treatment of both compounds with methyl-lithium in diethyl ether resulted in one electron reduction of the metal center and gamma-deprotonation of one of the ligands. The dimeric {U[(mu-CH(2)-SiMe(2))N(SiMe(3))](2)[mu-Li(DME)]}(2) (1) was isolated from the reaction mixture regardless of the amount of MeLi employed. The employment of LiCH(2)SiMe(3) in DME led instead to multiple gamma-deprotonation events at the same carbon atom with formation of the trimetallic {U[(mu-CH(2)-SiMe(2))N(SiMe(3))][N(SiMe(3))(2)]}(2){U[(mu(3)-C-SiMe(2))N(SiMe(3))][N(SiMe(3))(2)]}{mu-OMe} (2) cluster centered on a fully deprotonated carbon atom. Crystallographic analysis revealed the presence of mu-OCH(3) units in the cluster as generated by DME solvent cleavage. A similar reaction carried out in the absence of DME led to the isolation of a closely related trimetallic {U[mu-(CH(2)-SiMe(2))N(SiMe(3))][N(SiMe(3))(2)]}(2){U[(mu(3)-C-SiMe(2))N(SiMe(3))][(mu-CH(2)-SiMe(2))N(SiMe(3))]} (3). One additional gamma-deprotonated fragment replacing the bridging methoxy group of 2 was present in this case. The presence of a fully deprotonated carbon atom bridging three metal centers and of one silicon atom was confirmed by both X-ray structures and NMR data. An attempt to reduce UCl(2)[N(SiMe(3))(2)](2) with KC(8) in a coordinating solvent resulted in ligand scrambling with the formation of two products. The first is a trimeric U(III) cluster formulated as {U-mu-Cl[N(SiMe(3))(2)][DME]}(2){U-mu-Cl[N(SiMe(3))(2)](2)}{mu(3)-Cl}(2) (4). The second was U[N(SiMe(3))(2)](3). A similar reduction reaction carried out in noncoordinating toluene resulted instead in an attack on the ligand affording the dimeric {U-mu-Cl[N(SiMe(3))(2)](2)[ horizontal lineN(SiMe(3))]}(2) (5). Alkylation of UCl(2)[N(SiMe(3))(2)](2) with n-butyl-lithium in hexane surprisingly yielded the pentavalent U[(mu-CH(2)-SiMe(2))N(SiMe(3))](2)[N(SiMe(3))(2)] (6). The acquisition of one additional ligand during the reaction hinted at the presence of other products in the reaction mixture.
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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) | 0.000 | 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 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".