Zirconium Complexes of a Cross-Bridged Cyclam
Bibliographic record
Abstract
The acid−base reaction of tetrabenzylzirconium with 1,4,8,11-tetraazabicyclo[6.6.2]hexadecane (H 2 (CBC), 1 ) produces (CBC)Zr(CH 2 Ph) 2, 2 . Similarly, reaction of 2 with phenols yields (CBC)Zr(CH 2 Ph)(O-2,6-C 6 H 3 Bu t 2 ), 3, and (CBC)Zr(O-2,6-C 6 H 3 Me 2 ) 2, 5 . Prolonged heating of 3 leads to the metalated product (CBC)Zr[κ 2 (C,O)-OC 6 H 3 (6-Bu t )(2-CMe 2 CH 2 )], 4 . Reaction of ZrCl 2 [N(SiMe 3 ) 2 ] 2 with H 2 (CBC) leads to (CBC)ZrCl 2, 6, which subsequently affords (CBC)Zr(X)(Y) by salt metathesis ( 7, X = Cl, Y = N(SiMe 3 ) 2; 8, X = Y = CH 3; 9, X = Y = CH 2 Si(CH 3 ) 3 ). Compounds 3 and 7 show restricted rotation about the Zr−O and Zr−N bonds, respectively, on the NMR time scale. For 3, the energy of activation for this process was determined to be 69 ± 1 kJ/mol. Neither 6 nor 8 shows ethylene polymerization activity when treated with 500 equiv of MAO. Reaction of 6 with 2 equiv of n-BuLi in the presence of excess diphenylacetylene leads to the zirconacyclopentadiene 10, (CBC)Zr(C 4 Ph 4 ). The structures of 5, 9, and 10 have been determined by X-ray crystallography, and all three display distorted octahedral geometry.
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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) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.001 | 0.001 |
| 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 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".