<i>N</i>,<i>N</i>-dimethylhydroxamidovanadium(V). Interactions with sulfhydryl-containing ligands: V(V) equilibria and the structure of a V(IV) dithiothreitolato complex
Bibliographic record
Abstract
The major aqueous equilibrium complexation reactions of vanadate in the presence of N,N-dimethylhydroxylamine (DMHA) and with dithiothreitol (DTT), β-mercaptoethanol, glycine, or cysteine in solution have been studied using 51 V NMR spectroscopy. Previously unreported DMHA complexes of 2:1 and 2:3 V:DMHA stoichiometry were observed and characterized. Concentration studies showed that, for the three sulphur-containing ligands, the major product of sulphur coordination has a 1:2:1 stoichiometry of vanadate to dimethylhydroxylamine to heteroligand. These products do not carry a charge in neutral to moderately basic solution. A second product type of 1:1:1, V to DMHA to heteroligand, stoichiometry is also formed. These products carry a single negative charge. A reductive reaction between vanadate and excess DTT to form a V(IV) complex was also observed and a solid product was isolated. This product could also be obtained by direct reaction of vanadyl sulphate with DTT. It was characterized by X-ray diffraction studies. Crystal structure of [{VO(SCH 2 CHOHCHOCH 2 S)} 2 ] [AsPh 4 ] 2 : monoclinic, space group P2 1 /n, Z = 2, a = 10.1607(18) Å, b = 17.8255(42) Å, c = 15.1520(33) Å, β = 104. 000(15)°, V = 2662.8 Å 3 , R F = 0.038 for 2327 data (I o [Formula: see text] 2.5σ(I o )) and 325 variables.Key words: vanadate, vanadyl, dithiothreitol, mercaptoethanol, cysteine, glycine, equilibrium constants, crystal structure, X-ray, vanadium NMR.
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.001 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.002 | 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".