Understanding the Role Structural Changes Play in the Formation of Strong and Weak Hydrogen Bonds in Tetramethylalkyldiammonium Dithiocyanate Salts
Bibliographic record
Abstract
Structural analyses for a series of tetramethylalkyldiammonium dithiocyanate salts have been carried out on low-temperature and high-resolution X-ray diffraction data. This series of organic salts contains both strong and weak hydrogen bonds which vary depending on the number of methylene groups bridging the two ammonium portions of the molecules. The S−N···H angles associated with the strong N−H···N hydrogen bonds in this series progressively decrease as the length of the alkyl bridge increases (ethylene > propylene > butylene). This results in less linear interaction between the N−H donor groups and the lone pair of the N acceptor atoms. The N,N,N′,N′-tetramethylpropylenediammonium and N,N,N′,N′-tetramethylbutylenediammonium dithiocyanate salts also produce weak C−H···N hydrogen bonds. The C−H···N and N−H···N interactions in this series undergo bifurcation, while one set of C−H···N and N−H···N hydrogen bonds in the propylene salt appears to experience a cooperative effect. A comparison of the topological properties of the electron density has shown a number of similarities and differences in the electronic nature of the strong and weak interactions in all three salts. This has all led to a better understanding of the electronic nature of these interactions and how they logically distribute themselves in the crystalline state.
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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 | 0.001 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 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 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".