Mechanistic Insight into H/D Exchange by a Pentanuclear Ni–H Cluster and Synthesis and Characterization of Structural Analogues of Potential Intermediates
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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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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) | 0.000 | 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) | 0.001 | 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 it