On the structural diversity anions coordinate to the butterfly-shaped [(R<sub>2</sub>Sn)<sub>3</sub>O(OH)<sub>2</sub>]<sup>2+</sup> cations and vice versa
Bibliographic record
Abstract
The syntheses and crystal structures of [(t-Bu2Sn)3O(OH)2]CO3·3MeOH, 1a, [(t-Bu2Sn)3O(OH)2]CO3·3H2O·acetone, 1b, [(t-Bu2Sn)3O(OH)2][I]2·[(t-Bu2Sn(OH)I]2·2DMSO, 1c, and [(Cy2Sn)3O(OH)2][I]2·2DMSO, 2a, all containing the trinuclear [(R2Sn)3O(OH)2]2+ ion have been described. The butterfly shape of this cation is derived from two annulated, four-membered tin–oxygen rings with a central μ3-oxygen atom and trigonal-bipyramidally coordinated tin atom both belonging to both rings and two μ2-hydroxyl groups and two outer, four-fold coordinated tin atoms. In 1a and 1b, the carbonate anions interact with the outer tin atoms of the cations as bidentate chelating ligands in the classical syn–syn coordination mode, and vice versa. In this way, both outer tin atoms expand their coordination sphere from four to five, with the consequence that bond angles and lengths within the cation are determined by the axial and equatorial position of the oxygen atoms within the trigonal-bipyramidal coordination on all three tin atoms. 1c consists of two different building units, an up to now unknown hydroxide iodide of composition [(t-Bu2Sn(OH)I]2 with hydrogen-bonded DMSO molecules and a [(t-Bu2Sn)3O(OH)2]2+ cation with one coordinated and one isolated, via hydrogen bonds connected iodine ion. The hydroxide iodine is built up of two five-fold coordinated tin atoms linked via two hydroxyl groups with exocyclic iodine atoms occupying axial positions at the trigonal-biypramidally coordinated tin atoms. The unprecedented coordination of the iodine ion to the [(t-Bu2Sn)3O(OH)2]2+ cation takes place between both outer tin atoms, resulting in a five-fold, trigonal-bipyramidal coordination at these tin atoms, too. Structural parameters within the so-formed [(t-Bu2Sn)3O(OH)2I]+ complex are very similar to those of 1a and 1b, with the exception of a significant lengthening of the tin–oxygen bonds opposite to the bridging iodine atom. 2a represents the first example of the [(R2Sn)3O(OH)2]2+ cation without R = t-butyl, so far. In the solid, it consists of two crystallographic independent [(Cy2Sn)3O(OH)2][I]2 building units, each connected to two DMSO molecules via hydrogen bonds. Both building units are very similar with respect to their conformation. Each of the iodine anions coordinates with only one of the two outer tin atoms, one in an inwards, one in an outwards to the tin-oxygen framework directed position. These tin atoms are therefore also trigonal-bipyramidally coordinated as in 1a−1c, but because of steric reasons one of the trigonal-bipyramids has changed its orientation within the tin–oxygen framework, accompanied by enormous changes of bond lengths and angles therein.
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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 | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
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".