Na<sub>6</sub>ZnSn<sub>2</sub>, Na<sub>4.24</sub>K<sub>1.76(1)</sub>ZnSn<sub>2</sub>, and Na<sub>20</sub>Zn<sub>8</sub>Sn<sub>11</sub>: Three Intermetallic Structures Containing the Linear {Sn−Zn−Sn}<sup>6−</sup> Unit
Bibliographic record
Abstract
The novel intermetallic compounds Na6ZnSn2 (1), Na4.24K1.76(1)ZnSn2 (2), and Na20Zn8Sn11 (3) were obtained from direct fusion of the pure elements, and their structures were determined by single crystal X-ray diffraction. All three compounds adopt new structure types and contain linear anionic {Sn-Zn-Sn}6- units with rather short Zn-Sn contacts (2.55-2.58 A), separated by alkali metal counterions. Compound 3 comprises layers of interconnected heteroatomic {Zn7Sn5} icosahedra as an additional unique structural motif. The bonding situation in this 16 valence-electron anion is analyzed by quantum chemical methods. The results of NBO, AIM, and ELF calculations (Gaussian03 on HF/3-21G level) reveal covalent bonding between Sn and Zn. The relationship to isovalent CO2 is discussed. Band structure calculations on the density functional theory level (LMTO) show that 1 can be understood as a Zintl phase containing a {Sn-Zn-Sn}6- anion; however, Na-Sn contacts must also be considered. Magnetic susceptibility measurements show a temperature-independent, weak diamagnetism for Na6ZnSn2 (1).
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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 | 0.005 | 0.003 |
| Meta-epidemiology (narrow) | 0.007 | 0.006 |
| Meta-epidemiology (broad) | 0.008 | 0.007 |
| Bibliometrics | 0.001 | 0.004 |
| Science and technology studies | 0.004 | 0.007 |
| Scholarly communication | 0.002 | 0.002 |
| Open science | 0.008 | 0.004 |
| Research integrity | 0.004 | 0.011 |
| 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; both teacher heads agree on what is shown here.
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".