Alkali Metal Amide Salts of a Bulky Nitrogen Tethered Phosphonium Fluorenide Ligand
Bibliographic record
Abstract
The reaction of a previously reported phosphine-imine ligand with 9-bromofluorene afforded a phosphonium bromide (E)-enamine that, upon deprotonation, affords an enamine tethered to a phosphonium fluorenide moiety. Isolation of various crystals of this enamine and subsequent analysis by single-crystal X-ray diffraction showed that both (E)- and (Z)-isomers occur, which is supported by three dynamic isomers in C 6 D 6 . 1 H NMR spectroscopy revealed that the enamine phosphonium fluorenide is the dominant isomer and is also observed within all four solid-state crystal structures of 3 . The solvent-free 3 and 0.5(THF, n-hexane) solvate of 3 occur as the (Z)-enamine, while co-crystallization of either diethyl ether or 3 molecules of THF resulted in the (E)-enamine of 3 . The ability for compound 3 to participate in two types of hydrogen bonds between either the methyne or amine protons with THF was observed from the 0.5(THF, n-hexane) and 3(THF) solvates, respectively. Subsequent deprotonation of the secondary amine with lithium-, sodium-, and potassium-containing bases yielded metal amides, forming mostly monomeric structures. Each alkali metal is chelated by one ligand with a coordinating solvent molecule (Et 2 O or THF), with the only exception being a potassium complex that lacked a coordinating solvent. This potassium complex has this donor vacancy filled by an intermolecular interaction with the backside of an adjacent 6-membered fluorenide ring, forming a polymer with n-hexane within the channels. This crystalline form readily de-solvates upon crushing and prolonged drying in vacuo. The single crystal X-ray structure of these complexes as various solvates with diethyl ether (Li, K), THF (Li, Na), and n-hexane (K) revealed the highly dynamic donor properties of the phosphonium fluorenide undergoing a wide range of η 2–6 interactions with the alkali metals.
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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 | 0.001 | 0.001 |
| 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 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.006 | 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 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".