The Supramolecular and Coordination Chemistry of Cobalt(II) Extraction by Phosphinic Acids
Bibliographic record
Abstract
A combination of mass spectrometry, DFT calculations and 31P{1H} NMR spectroscopy has been used to define the mode of action of the commercial cobalt extractant, bis(2,4,4‐trimethylpentyl)phosphinic acid (CYANEX®272, L1H) in Co recovery. The nature of the CoII complexes formed in the water‐immiscible phase is determined largely by the propensity of phosphinates to form strong interligand H‐bonds in the outer coordination sphere and also to form stable µ2‐Co–O–P–O–Co bridges. At low Co loading levels, the predominant species is the 4:1 complex, [Co(L1·L1H)2], in which coordinated neutral phosphinic acid ligands form strong H‐bonds to adjacent anionic phosphinates. At higher Co loading, oligomers such as [(L1·L1H)Co(L12Co)n(L1·L1H)] are formed with µ2‐phosphinate bridging, resulting in a substantial increase in the viscosity of the water‐immiscible phase. The presence of tris(2,4,4‐trimethylpentyl)phosphine oxide (L2) in the commercial formulation reduces the viscosity because its incorporation into oligomeric complexes such as [(L2)Co{L13CoL1CoL13Co}mL1] can terminate chains, resulting in a lower average molecular weight. The uptake of Zn by L1H shows a very similar dependence of viscosity on loading, and DOSY spectra and mass spectrometry demonstrate that higher molecular weight species are present at high Zn loading.
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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".