Synthesis and Characterization of RuH<sub>2</sub>(H<sub>2</sub>)<sub>2</sub>(P<sup>i</sup>Pr<sub>3</sub>)<sub>2</sub> and Related Chemistry. Evidence for a Bis(dihydrogen) Structure
Bibliographic record
Abstract
The complex RuH 2 (H 2 ) 2 (P i Pr 3 ) 2 ( 1 ) was prepared by the protonation of [K(18-crown-6)][RuH 5 (P i Pr 3 ) 2 ] with 1,3-benzenedimethanol. The observation of H−H and M−H vibrations, short T 1 (min) values of the hydride resonance, the octahedral geometry of the disordered single-crystal X-ray structure of 1, and large averaged H−D coupling constants for RuH x D 6 - x (P i Pr 3 ) 2 provide evidence for two dihydrogen and two hydride ligands. Under an atmosphere of N 2, complex 1 readily forms an equilibrium mixture of the dinitrogen complexes RuH 2 (N 2 ) 2 (P i Pr 3 ) 2 ( 2 ) and {RuH 2 (N 2 )(P i Pr 3 ) 2 } 2 (μ-N 2 ) ( 3 ), which readily reverts to 1 under an atmosphere of H 2 . Slow evaporation of a pentane solution of 1 under an atmosphere of N 2 gas resulted in the isolation of colorless crystals of 3 . Complex 1 is very unstable with respect to loss of H 2 and forms the trihydride-bridged classical polyhydride dimer (P i Pr 3 ) 2 (H)Ru(μ-H) 3 Ru(H) 2 (P i Pr 3 ) 2 ( 4 ) under an argon atmosphere or under vacuum at room temperature. Exposure of a solution of 4 to H 2 gas results in the gradual regeneration of 1 . Similarly, the known bis(dihydrogen) complex RuH 2 (H 2 ) 2 (PCy 3 ) 2 ( 5 ) was also prepared by protonation of [K(18-crown-6)][RuH 5 (PCy 3 ) 2 ]. An attempt to isolate RuH 2 (H 2 ) 2 (PPh 3 ) 2 ( 6 ) by protonation of K[RuH 5 (PPh 3 ) 2 ] resulted in the in situ formation of an equilibrium mixture of the bis(dihydrogen) complex 6 and the nonclassical dimer (PPh 3 ) 2 (H)Ru(μ-H) 3 Ru(H 2 )(PPh 3 ) 2 ( 7 ). The crystal structures of 3, 4, and 7 are reported.
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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) | 0.001 | 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 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".