Silyl Hydrides of Tantalum Supported by Cyclopentadienyl-imido Ligand Sets: Syntheses, X-ray, NMR, and DFT Studies
Bibliographic record
Abstract
Reactions of the imido complex Cp(ArN)Ta(PMe 3 ) 2 ( 1, Ar = 2,6-diisopropylphenyl) with silanes afford the silyl hydrides Cp(ArN)Ta(PMe 3 )(H)(SiR n Cl 3− n ) ( 2b − e ) and Cp(ArN)Ta(PMe 3 )(H)(SiPhMeH) ( 2a ) as the first kinetic products. However, the hydride compounds Cp(ArN)Ta(PMe 3 )(H)(SiR n Cl 3− n ) are metastable and, first, rearrange in the presence of phosphine to the chlorides Cp(ArN)Ta(PMe 3 )(Cl)(SiHR n Cl 2− n ) ( 5 ) and then decompose to Cp(ArN)Ta(PMe 3 )(Cl)(H) ( 4 ) and eventually to Cp(ArN)Ta(PMe 3 )Cl 2 ( 3 ). Complexes with a smaller Ar′ substituent at nitrogen (Ar′ = 2,6-dimethylphenyl) react faster, as do more Lewis acidic silanes. The occurrence of interligand hypervalent interactions in the tantalum complexes Cp(ArN)Ta(PMe 3 )(H)(SiR n Cl 3− n ) has been revealed by X-ray structure analysis, DFT calculations, and the experimental determination of the sign of the coupling constant J (Si−H). The J (Si−H) was found to be negative for Cp(ArN)Ta(PMe 3 )(H)(SiMe n Cl 3− n ) ( J (Si−H) = −40 Hz for n = 1; J (Si−H) = −50 Hz for n = 0), indicative of the presence of Si−H bonding, but positive for Cp(ArN)Ta(PMe 3 )(H)(SiMeHPh) ( J (Si−H) = +14 Hz), suggesting the absence of direct Si−H interactions. A DFT study of the mechanism of silane coupling with the model imido complex Cp(MeN)Ta(PMe 3 ) 2 established the feasibility of the direct addition of silanes HSiMe n Cl 3− n ( n = 1−3) to the imido group to give the adduct Cp(MeN{→SiR 3 -H})Ta(PMe 3 ) 2, as previously found in the related niobium chemistry.
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 | 0.001 |
| 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 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.009 | 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".