Synthesis and reactivity of Li and TaMe<sub>3</sub> complexes supported by N,N′-bis(2,6-diisopropylphenyl)-o-phenylenediamido ligands
Bibliographic record
Abstract
The dilithium complex of N,N'-bis(2,6-diisopropylphenyl)-o-phenylenediamide, [Li2L(thf)3], reacts with TaMe3Cl2 in THF/Et2O to yield [Li(Et2O)(thf)LTaMe3Cl] in which the phenylene backbone of (2-) is bound η(4) to the Ta centre. This dinuclear species reacts with MeLi to yield the tetramethyltantalum complex [Li(Et2O)(thf)LTaMe4]. Double deprotonation of N,N'-bis(2,6-diisopropylphenyl)(4,5-dimethyl)-o-phenylenediamine (H2L') in Et2O yielded the dilithium complex [Li2L'(OEt2)2]. The two additional methyl groups on L'(2-) change the observed reactivity towards TaMe3Cl2: rather than bridging between Ta and Li, ligand oxidation occurs to afford mononuclear [LiL'(OEt2)]. This monolithium radical species, which was characterized by EPR spectroscopy, can also be synthesized using the more conventional oxidant AgBF4. Double deprotonation of H2L with KCH2Ph in toluene followed by reaction with TaMe3Cl2 furnished [TaLMe3]. Preliminary reactivity studies show [TaLMe3] reacts with unsaturated substrates N,N'-dicyclohexylcarbodiimide and mesityl azide to undergo migratory insertion into one of the Ta-C bonds: the corresponding amidinate and triazenido ligands are generated. When subjected to UV irradiation, [TaLMe3] undergoes reduction accompanied by loss of a methyl group to yield the dimeric species [TaLMe2]2.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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 source (direct Gemma or distilled Codex), 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".