Vanadium(V) Tartrato Complexes: Speciation in the H<sub>3</sub>O<sup>+</sup>(OH<sup>-</sup>)/H<sub>2</sub>VO<sub>4</sub><sup>-</sup>/(2<i>R</i>,3<i>R</i>)-Tartrate System and X-ray Crystal Structures of Na<sub>4</sub>[V<sub>4</sub>O<sub>8</sub>(<i>rac</i>-tart)<sub>2</sub>]·12H<sub>2</sub>O and (NEt<sub>4</sub>)<sub>4</sub>[V<sub>4</sub>O<sub>8</sub>((<i>R</i>,<i>R</i>)-tart)<sub>2</sub>]·6H<sub>2</sub>O (tart = C<sub>4</sub>H<sub>2</sub>O<sub>6</sub><sup>4</sup><sup>-</sup>)
Bibliographic record
Abstract
A study of the aqueous H3O+(OH-)/H2VO4-/(2R,3R)-tartrate system has been performed at 273 K in a 1.0 mol/L Na+(Cl-) ionic medium using 51V NMR spectroscopy. In this relatively complicated system, more than 12 different species were observed. Ligand concentration, vanadate concentration, and pH variation studies were carried out, particularly for the range of pH 5.8-8.0 and for pH 2.4. Chemical shifts, vanadium-ligand stoichiometry, and also composition and formation constants for some, but not all, species are given. Despite some reduction of vanadium(V) to vanadium(IV) in an acidic medium at pH approximately 2.4, the stoichiometries of the principal species in solution at this pH were determined. Electrospray ionization mass spectra for some solutions were obtained and were in accordance with the conclusions drawn from the speciation studies. A series of crystalline vanadium(V) tartrato complexes M4[V4O8(tart)2].aq were also prepared and characterized. X-ray diffraction studies of Na4[V4O8(rac-tart)2].12H2O (1) and (NEt4)4[V4O8((R,R)-tart)2].6H2O (2) revealed unique tetranuclear [V4O8(tart)2]4- ions for which the {V4O4} rings have boat conformations.
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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 | 0.025 | 0.011 |
| Meta-epidemiology (narrow) | 0.042 | 0.049 |
| Meta-epidemiology (broad) | 0.035 | 0.019 |
| Bibliometrics | 0.015 | 0.032 |
| Science and technology studies | 0.018 | 0.020 |
| Scholarly communication | 0.014 | 0.019 |
| Open science | 0.027 | 0.015 |
| Research integrity | 0.030 | 0.042 |
| Insufficient payload (model declined to judge) | 0.001 | 0.008 |
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; both teacher heads agree on what is shown here.
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".