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)
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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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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) | 0.001 | 0.001 |
| 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 | 0.000 |
| 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 it