Solid-state and solution structures of hetero-aggregates formed between nBuLi and NCN pincer aryl lithium
Bibliographic record
Abstract
The reaction of NCNLi pincers (NCN = [2,6-(R(2)NCH(2))(2)C(6)H(3)](-), R = Me (), Et ()) with various equivalents of nBuLi in non-polar solvent results in the generation of novel mixed alkyl-aryl organolithium hetero-aggregates. The identification (variable temperature (1)H, (13)C, (7)Li and 2D NMR spectroscopy and X-ray crystallography) of multiple, equilibrating mixed-aggregates that form in these reactions has been achieved. Fluxional processes in the parent [NCNLi](2) dimeric homo-aggregates were re-evaluated and Li-N bond rupture was found to be in operation, a prerequisite towards further aggregation chemistry. The crystallized aggregates, with the formula (2).[nBuLi](2) or (2).[nBuLi](2), shows one amine arm from each NCNLi fragment stabilizing a [nBuLi](2) dimer. The core of the aggregates exhibit a roughly cubic Li(4)C(4) configuration with each aryl carbanion eta(3) coordinated to Li(3) triangular faces. Dissolution of microcrystalline powders of (2).[nBuLi](2) or (2).[nBuLi](2) regenerates the observed equilibria. Based on the NMR data, the remaining mixed aggregates are proposed to have the formula .[nBuLi](3) and .[nBuLi](3), respectively; the solution structure is again based on a Li(4)C(4) cluster. The relative concentration of the constituents in these equilibria was found to vary depending on the steric size of the amine groups. In the case of , the predominant species is the (2).[nBuLi](2) aggregate while for , the dimer (2) is favoured.
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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 | 0.000 |
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 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".