Synthesis and characterization of two new "pincer" complexes of zinc(II). The X-ray crystal structures of the five coordinate complexes [ZnCl<sub>2</sub>{η<sup>3</sup>-<i>NN</i>'<i>N</i>-2,6-(R<sub>2</sub>NCH<sub>2</sub>)<sub>2</sub>C<sub>5</sub>H<sub>3</sub>N}] (R = <i>n</i>-Bu or Me)
Bibliographic record
Abstract
The potentially terdentate NN'N donor ligand 2,6-bis[di-(n-butyl)aminomethyl]pyridine (1) does not form a stable, isolable Ru complex using any standard Ru starting materials. This is in contrast to the dimethylamino derivative 2. In the presence of Zn metal as a reducing agent, the treatment of hydrated ruthenium trichloride with 2 leads instead to the isolation of a diamagnetic Zn(II) complex (3) of general formula [ZnCl2(1)]. Analysis of 3 (NMR, X-ray) reveals the complex to be a mononuclear Zn halide compound containing ligand 1 in an η3-NN'N bonding motif. The Zn atom is found to be five-coordinate and in a geometry best described as midway between trigonal bipyramidal and square pyramidal in structure. Similar experiments using 2 produce an analogous Zn species (4) which has likewise been fully characterized (NMR, X-ray) and found to be similar to 3 although the metal is in a distinctly square pyramidal environment. These compounds are viewed as relatives of the class of Zn "pybox" catalysts.Key words: pincer complexes, zinc(II) compounds, X-ray crystal structure.
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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 | 0.001 |
| 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 | 0.001 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".