Unusual Redox Chemistry of Ytterbium Carbazole–Bis(oxazoline) Compounds: Oxidative Coupling of Primary Phosphines by an Ytterbium Carbazole–Bis(oxazoline) Dialkyl
Bibliographic record
Abstract
The 1,8-bis(4′,4′-dimethyloxazolin-2′-yl)-3,6-di- tert -butylcarbazole anion (Czx) forms monomeric, six-coordinate halide complexes of Yb(II), (Czx)Yb(X)(THF) 2 (X = I ( 2 ), Cl ( 3 )), by metathesis of YbX 2 with NaCzx ( 1 ) or Na/Hg reduction of (Czx)Yb(Cl) 2 (THF). The crystal structure of 1 reveals a polymeric chain structure in which the oxazoline ring bridges to the Na + of an adjacent unit. The iodo complex 2 serves as a precursor to divalent silylamide, alkyl, and phosphide complexes, (Czx)Yb(X)(THF) n ( 4, X = N(SiMe 3 ) 2, n = 1; 5, X = CH(SiMe 3 ) 2, n = 1; 7a, X = 2,4,6-Me 3 C 6 H 2 PH, n = 2; 7b, X = 2,4,6-Pr i 3 C 6 H 2 PH, n = 2). The X-ray structure of 4 reveals a distorted-trigonal-bipyramidal geometry with the Czx ligand occupying two axial sites and one equatorial site in a pseudo- mer coordination mode. In contrast to the typical metathesis chemistry observed with LiCH(SiMe 3 ) 2, an unusual oxidation occurs when 2 or 3 is treated with LiCH 2 SiMe 3 to generate the previously isolated trivalent alkyl (Czx)Yb(CH 2 SiMe 3 ) 2 . Trivalent Yb complexes with the Czx ligand also display unusual redox chemistry: rapid reduction to the Yb(II) phosphides 7a, b is observed on treatment of mer,cis -(Czx)Yb(Cl) 2 (THF) with ArPH – Na + ( 6a, b ) or, equivalently, on treatment of (Czx)Yb(CH 2 SiMe 3 ) 2 with ArPH 2 . In both cases, oxidative coupling of the phosphide or phosphine was observed to form meso - and rac -biphosphines, ArPH–PHAr (Ar = 2,4,6-Me 3 C 6 H 2 ( 9a ), 2,4,6-Pr i 3 C 6 H 2 ( 9b )).
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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".