The suppression of lone-pair stereoactivity in [Cu+(As3+O3)4] clusters in dixenite: A tribute to Paul B. Moore
Bibliographic record
Abstract
Abstract The crystal structure of dixenite, ideally Cu+Fe3+Mn142+(As5+O4)(As3+O3)5(SiO4)2(OH)6, from Långban, Sweden, was refined to an R1-index of 1.58%, and the structure proposed by Araki and Moore (1981) was confirmed and details elucidated. The structure, crystallizing in space group R3 with a = 8.2204(3) and c = 37.485(3) Å, consists of layers of (Mn2+,Fe3+)(O,OH)6 octahedra linked by (As5+O4) and (SiO4) tetrahedra, (As3+O3) trigonal pyramids, and (CU+As43+) tetrahedra. There are five distinct layers in the repeat unit of the cell, four of which are very similar to the layers in mcgovernite. An unusual aspect of one of the trimers of octahedra is that there is a triangular-prismatic hole through the center of the cluster. The (CU+As43+) tetrahedra are parts of larger clusters: [Cu+(As3+O3)4] in which four (As3+O3) groups link to a central Cu+ that occupies the positions normally taken by the stereoactive lone-pairs of electrons that generally characterize As3+ in triangular-pyramidal coordination by O. Thus, the stereoactive lone-pair behavior that is characteristic of (As3+O3) trigonal pyramids is suppressed by the coordination of Cu+ by four As3+ ions.
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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) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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 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".