Use of Olefin Metathesis to Link Phosphinimide−Cyclopentadienyl Ligand Complexes: Synthesis, Structure, and Ethylene Polymerization Activity
Bibliographic record
Abstract
Efforts to link phosphinimide and cyclopentadienyl ligands via metathesis were undertaken. To this end, the allylic phosphinimine t- Bu 2 (CH 2 ═CHCH 2 C(Me 2 )PNSiMe 3 ( 1 ) and the Ti complexes t- Bu 2 (CH 2 ═CHCH 2 C(Me 2 )PNTi(Cp)Cl 2 ( 2 ), t- Bu 2 (CH 2 ═CHCH 2 C(Me 2 )PNTi(C 5 Me 5 )Cl 2 ( 3 ), and t- Bu 2 (CH 2 ═CHCH 2 C(Me 2 )PNTi(C 5 H 4 CH 2 CH═CH 2 )Cl 2 ( 4 ) were prepared. Attempts to effect olefin metathesis on 4 using either [Cl 2 (PCy 3 ) 2 Ru═CHPh] or [Cl 2 (PCy 3 )(H 2 IMes)Ru═CHPh] as the catalyst were unsuccessful. Alternatively, the phosphinimine t- Bu 2 (CH 2 ═CHCH 2 )PNSiMe 3 ( 5 ) was found to undergo olefin isomerization upon conversion to the phosphinimines t- Bu 2 (MeCH═CH)PNH ( 6 ) and t- Bu 2 (MeCH═CH)PNTi(NMe 2 ) 3 ( 7 ), t- Bu 2 (MeCH═CH)PNTiCl 3 ( 8 ), and t- Bu 2 (MeCH═CH)PNTiCl 3 (THF) ( 8 ·THF). Direct reaction of 5 with TiCl 4 gave t- Bu 2 (CH 2 ═CHCH 2 )PNTiCl 3 ( 9 ), which was readily converted to t- Bu 2 (CH 2 ═CHCH 2 )PNTi(C 5 H 4 C(Me)═CH 2 )Cl 2 ( 10 ). Repeated attempts to effect a ring closure by olefin metathesis resulted in no reaction. However, the species t- Bu 2 (CH 2 ═CHCH 2 )PNTi(CpCH 2 CH═CH 2 )Cl 2 ( 11 ) was readily methylated to give t- Bu 2 (CH 2 ═CHCH 2 )PNTi(CpCH 2 CH═CH 2 )Me 2 ( 12 ), and 11 in the presence of [Cl 2 (PCy 3 ) 2 Ru═CHPh] underwent olefin metathesis to give t- Bu 2 (CpCH 2 CH═CHCH 2 )PNTiCl 2 ( 13 ). Subsequent reaction with 9-BBN gave t- Bu 2 (CpCH 2 CH 2 CH(B(C 8 H 14 )CH 2 )PNTiCl 2 ( 14 ), while alkylation gave t- Bu 2 (CpCH 2 CH═CHCH 2 )PNTiMe 2 ( 15 ). In a similar fashion, the species t- Bu 2 (C 5 Me 4 CH 2 CH═CHCH 2 )PNTiCl 2 ( 20 ), t- Bu 2 (C 5 Me 4 CH 2 CH═CHCH 2 )PNTiMe 2 ( 21 ), t- Bu 2 (C 9 H 6 CH 2 CH═CHCH 2 )PNTiCl 2 ( 24 ), and t- Bu 2 (C 9 H 6 CH 2 CH═CHCH 2 )PNTiMe 2 ( 25 ) were prepared. A number of these compounds were screened for their ability to effect olefin polymerization using MAO, B(C 6 F 5 ) 3, or [Ph 3 C][B(C 6 F 5 ) 4 ] as the activator. In general, active single-site catalysts were obtained, yielding high molecular weight polyethylene, although the activities were lower with MAO than with boron-based activators. Crystal structures of 3, 8 ·THF, 13, 15, and 20 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 | 0.001 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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) | 0.007 | 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".