Rapid and selective formic acid dehydrogenation catalysis by molecular ruthenium hydrides supported by rigid PCcarbeneP pincer ligands
Bibliographic record
Abstract
A series of four molecular ruthenium hydrido complexes supported by previously reported rigid PCcarbeneP pincer ligand frameworks were evaluated as formic acid dehydrogenation (FAD) catalysts. The ligands in the complexes LRRu(H)X (R = H, NMe2; X = Cl, kappa-2-O2CH) differ in the electron richness by substitution on the aryl groups linking the di-iso-propylphosphine arms to the central carbene donor. We find that only the unsubstituted (R = H) chloro and formato complexes are effective catalyst precursors; the NMe2 substituted derivatives decompose under catalytic conditions. However, the two compounds LHRu(H)X are highly active (TOF = 1300-4200 h-1), long lived (TON up to 122 000) and selective (dihydrogen and carbon dioxide are the sole products) at 21˚C with no base additives necessary in 13M formic acid in water/dioxane. These performance metrics compare well with state of the art catalysts operating under ambient conditions. Mechanistic experiments support a simple two-step mechanism involving rate limiting protonolysis of the Ru-H by formic acid to release H2 and rapid loss of CO2 via -elimination from the resulting formato complex. This second step is facilitated kinetically because the donor properties of the X ligands lower the barrier to formation of the 1 binding mode for the formato ligand, needed to access the -elimination transition state for CO2 loss. Structural and DFT studies support this notion.
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 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.001 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 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".