Unique molecular geometries of reduced 4- and 5-coordinate zinc complexes stabilised by diiminopyridine ligand
Bibliographic record
Abstract
Stepwise reduction of the diiminopyridine (dimpyr) complex, dimpyrZnCl2, by KC8 leads to molecular zinc compounds dimpyrZnCl (2) and dimpyrZnCl(DMAP) (3, DMAP = 4-dimethylaminopyridine), which were characterized by X-ray diffraction and EPR spectroscopy. Compound 2 shows an unusual nearly square planar geometry of the zinc atom equally ligated by two imine groups. X-ray crystallographic and EPR data suggest significant delocalization of the zinc 4p electron onto the non-innocent dimpyr ligand. The chloride in 2 can also be substituted by a methyl group upon addition of methyl lithium to generate compound 4, dimpyrZnMe. The novel alkylzinc compound displayed approximate square planar geometry around the zinc centre and significant delocalization of electron density onto the dimpyr ligand, as revealed by X-ray crystallographic studies and EPR spectroscopy, akin to 2. Further reduction of 3 leads to compound 5, dimpyrZn(DMAP)2. X-ray diffraction study of 5 revealed an unprecedented see-saw geometry around the four-coordinate zinc center with significant electron density transfer to the dimpyr ligand, supported by DFT calculations.
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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 | 0.001 | 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 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".