Bis(formamidine–urea) Complexes of Ni<sup>II</sup> and Cu<sup>II</sup>:Synthesis, Characterization, and Reactivity
Bibliographic record
Abstract
Abstract A novel chelating chiral bis(formamidine–urea) ligand was synthesized and used to prepare the corresponding NiII and CuII complexes. Spectroscopic and X‐ray crystallographic analysis of the former revealed that the urea moiety of the acyclic tetradentate ligand is deprotonated and binds to the square‐planar Ni2+ ion through amide nitrogen atoms. This complex showed quasi‐reversible redox behavior in cyclic voltammetry, with E1/2 = 640 mV vs. Cp2Fe+/Cp2Fe corresponding to the NiIII/NiII couple. The Cu complex was shown by EPR spectroscopy to also adopt a square‐planar geometry [g∥ = 2.25 (A∥ = 184 G), g⟂ = 2.06 at 6 K], and reduction was found to be irreversible, perhaps due to the rigid nature of the tetradentate ligand. The nickel complex was found to be a modestly active catalyst for epoxidation of electron‐richalkenes under Mukaiyama’s conditions, likely involving a radical mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
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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".