Influence of SiMe<sub>3</sub> Substituents on Structures and Hydrosilylation Activities of ((SiMe<sub>3</sub>)<sub>1</sub> <sub>or</sub><sub> </sub><sub>2</sub><b>-</b>Indenyl)Ni(PPh<sub>3</sub>)Cl
Bibliographic record
Abstract
This report examines the effect of substituents R on structures and reactivities of the complexes (R-Ind)Ni(PPh 3 )Cl (R-Ind = 1-Me-indenyl, 1; 1-SiMe 3 -indenyl, 2; 1,3-(SiMe 3 ) 2 -indenyl, 3 ). NMR studies indicate that a relatively facile dissociation of PPh 3 takes place in solutions of complex 3 (Δ G ⧧ ≈ 10 kcal/mol in C 6 D 6 ) but not those of complexes 1 and 2, implying that the presence of Ind substituents at the 1- and 3-positions can influence the kinetic lability of PPh 3 . X-ray analyses have also shown that the PPh 3 ligand and the SiMe 3 group adjacent to it in complex 3 experience some steric repulsion, which is manifested in angular deformations (out-of-plane bending of the SiMe 3 group by about 0.56−0.65 Å and 5−10° variations in the P−Ni−Cl and P−Ni−C3 angles) and a somewhat longer Ni−P bond (ca. 2.19 Å). Reactivity studies have shown that complexes 1 − 3 are effective precatalysts for the addition of PhSiH 3 to styrene in the presence of the cationic initiator NaBPh 4; α-addition of the silyl moiety takes place regioselectively to give PhCH(Me)(SiPhH 2 ). The catalytic activities depend on the styrene:PhSiH 3 ratio but not the Ind substituents; thus, catalytic turnover numbers increase from ca. 75 with a 1:1 ratio to ca. 95 with a 1:1.5 ratio for all three precursors. The hydrosilylation can also proceed in the absence of initiator, but in this case the activities are strongly dependent on Ind substituents, increasing in the order 1-Me-Ind ≪ 1-SiMe 3 -Ind < 1,3-(SiMe 3 ) 2 -Ind.
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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".