Cyclopentadienyl chromium diimine and pyridine-imine complexes: ligand-based radicals and metal-based redox chemistry
Bibliographic record
Abstract
Paramagnetic CpCr(III) complexes with antiferromagnetically-coupled anionic radical diimine and pyridine-imine ligands were prepared and characterized. The diimine chloro CpCr[(ArNCR)(2)]Cl complexes (1: Ar = 2,6-iPr(2)C(6)H(3) (Dpp), R = H; 2: Ar = 2,6-Me(2)C(6)H(3) (Xyl), R = Me; 3: Ar = 2,4,6-Me(3)C(6)H(2) (Mes), R = Me) were synthesized by treatment of previously reported Cr(diimine)(THF)(2)Cl(2) precursors with NaCp. Reduction of 1 with Zn gives CpCr[(DppNCH)(2)], 4, resulting from reduction of Cr(III) to Cr(II) with retention of the ligand-based radical. Alkoxide complexes CpCr[(DppNCH)(2)](OCR(2)R') (5: R = Me, R' = Ph; 6: R = iPr, R' = H) were synthesized by protonolysis of Cp(2)Cr with HOCR(2)R' in the presence of the neutral diimine and catalytic base. The corresponding radical pyridine-imine complexes CpCr(PyCHNMes)Cl (9), CpCr(PyCHNMes) (8), and CpCr(PyCHNMes)(OCMe(2)Ph) (11), were prepared by analogous routes. Oxidation of 8 with iodine gives CpCr(PyCHNMes)I (10) where oxidation of Cr(II) to Cr(III) again occurs with retention of the anionic pyridine-imine radical ligand. The molecular structures of complexes 1, 2, 4-8, 10 and 11 were determined by single-crystal X-ray diffraction. Unusual low energy bands were observed in the UV-vis spectra of the reported complexes, with particularly strong transitions observed for the Cr(II) complexes 4 and 8. The electronic structure of pyridine-imine complexes 8 and 10 were investigated by theoretical calculations.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.022 | 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".