A Polyselenide with a Novel Se<sub>7</sub><sup>8–</sup> Unit: the Structure of Sr<sub>19–<i>x</i></sub>Pb<i><sub>x</sub></i>Ge<sub>11</sub>Se<sub>44</sub> with <i>x</i> = 5.0 and 6.4
Why this work is in the frame
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Bibliographic record
Abstract
An unprecedented, planar Se 7 8– unit with a threefold rotation axis was discovered in the new polyselenide Sr 19– x Pb x Ge 11 Se 44 . Sr 12.6 Pb 6.4 Ge 11 Se 44 crystallizes in the non‐centrosymmetric hexagonal space group P 6 3 with unit cell dimensions of a = b = 19.9867(2) Å, c = 12.0546(1) Å, V = 4170.28(7) Å 3 , with two formula units per cell. Its structure contains isolated [GeSe 4 ] tetrahedra, [Ge 2 Se 7 ] dimers, and a novel, planar propeller‐shaped Se 7 8– unit. The latter is unprecedented, but reminiscent of the isoelectronic pyramidal Se 7 8– and I 7 – units. It consists of a central Se atom, to which three Se 2 pairs with a short Se–Se bond are attached through a longer Se–Se distance, resulting in a central Se atom featuring 120° bond angles, and bridging Se atoms featuring an approximately linear coordination with a 179° bond angle. It can thus be written as [Se(Se 2 ) 3 ] 8– . We characterized this unit using Gaussian calculations in comparison to the pyramidal Se 7 8– unit, which may be described also as [Se(Se 2 ) 3 ] 8– . The solid‐state material is a black semiconductor with an optical band‐gap of 1.8 eV, which supports the assignment of this charge.
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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 | 0.002 | 0.001 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.002 | 0.001 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.002 | 0.002 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.004 | 0.001 |
| Research integrity | 0.000 | 0.003 |
| 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