Mechanistic Insight into H/D Exchange by a Pentanuclear Ni–H Cluster and Synthesis and Characterization of Structural Analogues of Potential Intermediates
Bibliographic record
Abstract
Experiments to gain mechanistic insight into catalytic H/D exchange of unactivated arenes by [( i Pr 3 P)Ni] 5 H 6 ( 1 ) are described. The reaction order with respect to 1, arene substrate, and added i Pr 3 P were determined, as well as the temperature dependence of reaction rate. Site-selectivity data were obtained by monitoring the reaction of 1 with fluorobenzene and 2-methoxynaphthalene. H/D exchange competition reactions between arenes reacted with 1 were performed. The addition of an excess of Hg to a solution of 1 provided the new heterometallic cluster [( i Pr 3 P)Ni] 5 H 6 (μ 4 -Hg) ( 2 ); this species also undergoes H/D exchange with C 6 D 6, albeit more slowly than 1 . Reaction of cluster 1 with TlCp (Cp = C 5 H 5 ) gave (η 5 -Cp)Ni[( i Pr 3 P)Ni] 4 (μ 2 -H) 4 (μ 4 -Tl) ( 3 ) with the loss of H 2 . A similar transfer of cyclopentadienyl to Ni occurred when 1 was reacted with MgCp 2, to give (η 5 -Cp)Ni[( i Pr 3 P)Ni] 4 H 6 (μ 4 -MgCp) ( 4 ), but not H 2 loss. Reaction of 1 with cyclopentadiene gave the 5-coordinate hydride complex (η 5 -Cp)Ni[( i Pr 3 P)Ni] 4 (μ 2 -H) 4 (μ 5 -H) ( 5 ). The Cp* analogue, (η 5 -Cp*)Ni[( i Pr 3 P)Ni] 4 (μ 2 -H) 4 (μ 5 -H) ( 6 ) (where Cp* = C 5 Me 5 ), was synthesized by reacting 1 with LiCp* in THF, or by reaction of 1 with pentamethylcyclopentadiene.
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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 | 0.001 |
| 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".