Carbazole-bis(oxazolines) as Monoanionic, Tridentate Chelates in Lanthanide Chemistry: Synthesis and Structural Studies of Thermally Robust and Kinetically Stable Dialkyl and Dichloride Complexes.
Bibliographic record
Abstract
The carbazole-bis(oxazoline) ligand 1,8-bis(4′,4′-dimethyloxazolin-2′-yl)-3,6-di- tert -butylcarbazole (H-Czx, 14 ) was prepared and reacted with Ln(CH 2 SiMe 3 ) 3 (THF) 2 to afford the five-coordinate dialkyl complexes (Czx)Ln(CH 2 SiMe 3 ) 2 (Ln = Y, 15; Er, 16; Yb, 17 ) in high yield. Deprotonation of 14 with NaN(SiMe 3 ) 2, followed by reaction with LnCl 3 (THF) x, affords the six-coordinate dichloride complexes cis, mer -(Czx)Ln(Cl) 2 (THF) (Ln = Y, 18; Er, 19; Yb, 20 ). Dialkyl complexes 15 – 17 were also prepared by reaction of the dichloride complexes 18 – 20, respectively, with 2 equiv of LiCH 2 SiMe 3 . Complexes 16 – 20 were characterized by X-ray crystallography. The dialkyl complexes 16 and 17 display a five-coordinate trigonal-bipyramidal geometry with the Czx ligand spanning both axial and one equatorial site with the CH 2 SiMe 3 rotated such that the SiMe 3 groups sit over the carbazole ring system. The solution structure for 15 – 20 was found to be consistent with that in the solid state by NMR spectroscopy. However, paramagnetic dichloride 20 was shown by variable-temperature 1 H NMR studies to undergo rapid THF exchange by a dissociative process in toluene- d 8 solution (Δ H ‡ = 98 ± 10 kJ mol –1, Δ S ‡ = +185 ± 25 J mol –1 K –1 ). Treatment of dialkyl 18 with [Ph 3 C] + [B(C 6 F 5 ) 4 ] − cleanly produces the alkyl cation [(Czx)Y(CH 2 SiMe 3 )] + [B(C 6 F 5 ) 4 ] − ( 21 ) by 1 H NMR spectroscopy, but this species does not insert 2,3-dimethylbutadiene.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 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 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".