A POTENTIOMETRIC STUDY OF METAL CHELATES WITH PENTAETHYLENEHEXAAMINEOCTAACETIC ACID
Bibliographic record
Abstract
Abstract The protonation constants of pentaethylenehexaamineoctaacetic acid, PHOA, were determined by potentiometric titration in aqueous solution at an ionic strength of 0.10 M KNO3 and at 25°C. The formation constants of various metal-PHOA complexes were also obtained by titrating mixtures of metal to ligand in molar ratios of 1:1 and 2:1. Calculations were performed with the computer program BEST. Individual formation constants are reported for Co(II), Ni(II), Cu(II), Zn(II), Cd(II), Hg(II) and Pb(II) with PHOA as well as their related protonated species. The stabilities of the 1:1 and 2:1 complexes are similar in many respects to complexes formed with tetraethylenepentaamineheptaacetic acid (TPHA). The similarities in the stabilities of both the 1:1 and 2:1 complexes with PHOA and those with TPHA are explained in terms of ligand denticity and steric effects. Mercury(II)-PHOA complexes exhibited the highest formation constants, followed by copper(II)-PHOA complexes which had higher log K ML's than those for Co(II), Ni(II), Zn(II), Cd(II) and Pb(II).
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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 | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| 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 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.009 | 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".