Reduction of Titanium(IV)-Phosphinimide Complexes: Routes to Ti(III) Dimers, Ti(IV)-Metallacycles, and Ti(II) Species
Bibliographic record
Abstract
The redox chemistry of phosphinimide-containing group IV metal complexes has been investigated. Reaction of the simple phosphinimide species CpTi(NPR 3 )Cl 2 (R = Me 1, i -Pr 2 ) with Mg affords complexes formulated as [CpTiCl(μ-NPR 3 )] 2 (R = Me 3, i- Pr 4 ). In contrast, CpTi(NP t -Bu 3 )Cl 2 ( 5 ) is reduced by Mg to a putative Ti(II) species that can be intercepted by a variety of reagents including 2,3-dimethyl-1,3-butadiene, diphenylacetylene, phenylacetylene, bis(trimethylsilyl)acetylene, ethylene, and propylene to give monometallic metallacyclic complexes. In this fashion, the Ti(IV) metallacycles CpTi(NP t- Bu 3 )(CH 2 C(Me)C(Me)CH 2 ), 6, CpTi(NP t- Bu 3 )(CPh) 4, 7, CpTi(NP t- Bu 3 )(C(Ph)CHC(Ph)CH), 8, CpTi(NP t- Bu 3 )(η 2 -C 2 (SiMe 3 ) 2 ), 9, CpTi(NP t- Bu 3 )(CH 2 ) 4, 10, CpTi(NP t- Bu 3 )(CH 2 CHMe) 2, 15, and CpTi(NP t- Bu 3 )(CH 2 ) 2 (CPh) 2, 16, were prepared. Related intramolecular formation of metallacycle complexes was achieved upon reduction of Cp‘Ti( t- Bu 2 (2-C 6 H 4 Ph)PN)Cl 2 (Cp‘ = Cp 18, Cp* 19 ). The products [Cp‘Ti(NPtBu 2 (2-C 6 H 4 Ph)] (Cp‘ = Cp 20, Cp* 21 ) contained η 6 -interactions between Ti and the 2-phenyl substituent of the biphenyl unit. While Ti(II)-phosphinimide complexes have proven difficult to handle due to their reactivity, an unequivocal example of a Ti(II) species was obtained via reduction of Cp*Ti(NP t- Bu 3 )Cl 2 ( 11 ) with Mg in the presence of CO, affording the species Cp*Ti(NP t- Bu 3 )(CO) 2 ( 22 ). X-ray data for 4, 6, 7, 9, 10, 15, and 17 − 22 are reported.
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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) | 0.002 | 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".