Isolation of Intermediate-Valent Ce(III)/Ce(IV) Hydrolysis Products in the Preparation of Cerium Iodates: Electronic and Structural Aspects of Ce<sub>2</sub>(IO<sub>3</sub>)<sub>6</sub>(OH<i><sub>x</sub></i>) (<i>x</i> ≈ 0 and 0.44)
Bibliographic record
Abstract
The layered cerium iodates Ce 2 (IO 3 ) 6 (OH x ) [ x ≈ 0 ( 1 ) and 0.44 ( 2 )] have been prepared from the reaction of (NH 4 ) 2 Ce(NO 3 ) 6 with I 2 O 5 at 180 °C in aqueous media. The structure of these compounds consists of square antiprismatic Ce centers that are bound by bridging iodate anions and one bridging oxo anion. The structure of 2 differs from that of 1 in that the bridging oxo atom is partially protonated, resulting in significant lengthening of the Ce−O bond from 2.050(1) to 2.212(2) Å. This protonation also results in partial reduction of 1 from a formally all Ce 4+ compound to an intermediate-valent ion with both Ce 3+ and Ce 4+ that is visually observed with a color change in the crystals from bright yellow to dark brown for 1 and 2, respectively. Magnetic susceptibility measurements on 1 show there to be a small paramagnetic impurity phase that is consistent with about 1% Ce 3+ in the sample. Similar measurements on 2 show that it contains at least 22% Ce 3+, determined from a measured effective moment of 1.19(5) μ B /mol Ce. This result corresponds to a formulation of 2 as Ce 2 (IO 3 ) 6 (OH 0.44 ). Analysis of Ce L 3 -edge XANES spectra supports this formulation. UV−vis diffuse reflectance spectra indicate charge-transfer or delocalization of the 4f 1 electrons in 2 . These results are discussed in terms of an intermediate-valent state in 2 that is composed of f states on Ce and p states on the bridging O. Crystallographic data (193 K): 1, orthorhombic, space group Pnma, a = 6.8297(4) Å, b = 16.6725(9) Å, c = 14.2487(8) Å, Z = 4; 2, orthorhombic, space group Pnma, a = 6.8534(4) Å, b = 16.989(1) Å, c = 14.2404(8), Z = 4.
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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) | 0.000 | 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 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".