Reduction of Titanium Supported by a <i>σ</i>-/<i>π</i>-Bonded Tripyrrole Ligand: Ligand C−N Bond Cleavage and Coordination of Olefin and Arene with an Inverse Sandwich Structure
Bibliographic record
Abstract
The formally Ti(I)/Ti(II) mixed-valence toluene complex {2,5-[(C 4 H 3 N)CPh 2 ] 2 [C 4 H 2 N(Me)]}Ti ( μ, η 6 -C 7 H 8 )Ti[{2,5-[(C 4 H 3 N)CPh 2 ] 2 [C 4 H 2 N(Me)]}][K(DME) 2 ]·toluene ( 1 ) with an inverse sandwich type of structure has been obtained from the reduction of {2,5-[(C 4 H 3 N)CPh 2 ] 2 [C 4 H 2 N(Me)]}TiCl with potassium in toluene. The bridging molecule of toluene in the paramagnetic 1 shows a visible distortion due to a substantial amount of metal-to-ring back-bonding. Complex 1 was always the only detectable product, even in cases when lower than stoichiometric amounts of reductant were employed. DFT calculations have been carried out to elucidate the electronic structure of the mixed-valence 1 in order to clarify the reason for its apparent thermodynamic stability. The most energetically favorable model comprises two divalent Ti centers connected to an organic radical anion. The olefin adducts {2,5-[(C 4 H 3 N)CPh 2 ] 2 [C 4 H 2 N]}Ti( η 2 - trans- PhHC CHPh)[K(DME)] ( 2 ) and {2,5-[(C 4 H 3 N)CPh 2 ] 2 [C 4 H 2 N (Me)]}Ti( η 2 - trans -PhHC CHPh) ( 3 ) were obtained from identical reactions carried out in the presence of trans -stilbene. Complexes 2 and 3 may be regarded as the result of the oxidative addition of a transient divalent species to the trans -stilbene molecule. In the case of 2 however, the reaction is accompanied by the cleavage of the C−N bond of the π -bound alkylated pyrrole ring.
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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) | 0.002 | 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".