Synthesis and Reactivity of Neutral, Zwitterionic and Cationic Pentamethylcyclopentadienyl−Tantalum−Phosphinimide Complexes
Bibliographic record
Abstract
This paper focuses on the synthesis and reactivity of Cp*Ta(V)−phosphinimide complexes. Reaction of stoichiometric mixtures of Cp*TaCl 4 and phosphinimine R 3 PNSiMe 3 affords the complexes Cp*Ta(NPR 3 )Cl 3, R = t -Bu 1, i- Pr 2 . These species are readily derivatized to the alkylated complexes Cp*Ta(NPR 3 )Me 3, R = t -Bu 3, i- Pr 4; Cp*Ta(NP t -Bu 3 )(CH 2 Ph)Cl 2, 5; and Cp*Ta(NP t -Bu 3 )(CH 2 Ph)Me 2, 6 . Reaction with 3 equiv of BnMgCl afforded the robust alkylidene species Cp*Ta(NPR 3 )(CHPh)(CH 2 Ph), R = t -Bu 7, i- Pr 8 . Reaction of 7 with MeI gives the metallacycle Cp*Ta(NP t -Bu 3 )(η 2 -CHPhCH 2 )(CH 2 Ph), 9 . Alkylation of 1 and 2 with 2 equiv of EtMgCl results in formation of the complexes Cp*Ta(NPR 3 )(η 2 -C 2 H 4 )Cl, R = t -Bu 10, i- Pr 11, while further reaction of 10 with EtMgCl affords Cp*Ta(NP t -Bu 3 )(η 2 -C 2 H 4 )(CH 2 CH 3 ), 12 . Reaction of 1 with 1 equiv of B(C 6 F 5 ) 3 results in generation of the salt [Cp*Ta(NP t- Bu 3 )Cl 2 ][ClB(C 6 F 5 ) 3 ], 13, while the analogous reaction with Ph 3 C[B(C 6 F 5 ) 4 ] affords the related salt [Cp*Ta(NP t- Bu 3 )Cl 2 ][B(C 6 F 5 ) 4 ], 14 . The zwitterionic species Cp*Ta(NPR 3 )Me 2 (MeB(C 6 F 5 ) 3 ) (R = t- Bu 15, i- Pr 16 ) are derived via reaction of 3 or 4 with B(C 6 F 5 ) 3 . The analogous reaction of 3 and 4 with [Ph 3 C][B(C 6 F 5 ) 4 ] affords the related salts [Cp*Ta(NPR 3 )Me 2 ][B(C 6 F 5 ) 4 ] (R = t- Bu 17, i- Pr 18 ). Treatment of 10 with Ph 3 CB(C 6 F 5 ) 4, Ph 3 CBF 4, or B(C 6 F 5 ) 3 gives the complexes [Cp*Ta(NP t- Bu 3 )(Cl)CH 2 CH 2 CPh 3 ][B(C 6 F 5 ) 4 ], 20, [Cp*Ta(NP t- Bu 3 )(Cl)(CH 2 CH 2 CPh 3 )][BF 4 ], 21 and the zwitterionic species [Cp*Ta(NP t- Bu 3 )(Cl)(CH 2 CH 2 B(C 6 F 5 ) 3 )], 22, respectively. The relevance of this chemistry to the related group IV metal olefin polymerization catalysts is discussed and considered. X-ray structural studies of 1, 3, 5, 7, 9, 10, and 22 are reported.
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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) | 0.011 | 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".