Dinitrogen Labile Coordination versus Four-Electron Reduction, THF Cleavage, and Fragmentation Promoted by a (calix-tetrapyrrole)Sm(II) Complex
Bibliographic record
Abstract
A divalent calix-tetrapyrrole Sm complex, {[(−CH 2 −) 5 ] 4 -calix-tetrapyrrole}Sm(THF)[Li(THF)] 2 [Li(THF) 2 ](μ 3 -Cl) ( 1 ), reacts with dinitrogen to reversibly form the labile dinuclear complex [{[(−CH 2 −) 5 ] 4 -calix-tetrapyrrole}Sm[Li(THF)] 3 (μ 3 -Cl)] 2 (μ 2 -N 2 )·2THF ( 2 ). Further attack on 2 by two additional molecules of 1 afforded four-electron reduction of the coordinated dinitrogen and formation of the novel trinuclear dinitrogen complex [{[(−CH 2 −) 5 ] 4 -calix-tetrapyrrole} 2 Sm 3 Li 2 ](μ 3 -N 2 )[Li(THF) 2 ]·THF ( 5 ). The formation of this species, where one calix-tetrapyrrole ligand was abstracted from one of the three samarium centers, is accompanied by formation of {[(−CH 2 −) 5 ] 4 -calix-tetrapyrrole}[Li(THF)] 4 ( 6 ) and of the trivalent {[(−CH 2 −) 5 ] 4 -calix-tetrapyrrole}Sm(Cl){[Li(THF)] 3 (μ 3 -Cl)} ( 7 ). A THF degradation reaction occurs in parallel to the dinitrogen fixation process. During the formation of 2, complex 1 also reacts with THF to afford another mononuclear divalent Sm complex, {[(−CH 2 −) 5 ] 4 -calix-tetrapyrrole}Sm(THF)Li 2 [Li(THF)](μ 3 -OCH CH 2 ) ( 3 ). This species contains an enolate fragment in the molecular backbone and shows no reactivity with N 2 . Recrystallization of 3 from THF did not eliminate the enolate fragment but afforded instead another divalent complex, {[(−CH 2 −) 5 ] 4 -calix-tetrapyrrole}Sm(THF) 2 {Li[Li(THF)] 2 }(μ 3 -OCH CH 2 )·THF ( 4 ), also unreactive toward N 2 . Finally a slow THF deoxygenation process occurs during the formation of 2 and 5, affording a dinuclear trivalent oxo derivative [{[(−CH 2 −) 5 ] 4 -calix-tetrapyrrole}Sm[Li(THF)] 3 (μ 3 -Cl)] 2 (μ-O) ( 8 ).
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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".