An exploratory ab initio study on the conformations of ethylguanidine in its neutral [CH<sub>3</sub>-CH<sub>2</sub>-NH-C(=NH)NH<sub>2</sub>] and protonated [CH<sub>3</sub>-CH<sub>2</sub>-NH-C(NH<sub>2</sub>)<sub>2</sub>] forms
Bibliographic record
Abstract
To explore the conformation intricacies of the guanidine group in the arginine side chain, ab initio computations have been carried out with ethylguanidine and the ethyl guanidinium ion. HF computations have been performed using 3-21G and 6-31G basis sets and DFT calculations were carried out at the B3LYP/6-31G(d) level of theory. The ethyl guanidinium ion has a single isomer due to its internal symmetry, although this structure has at least three conformations. However, several structures were found and optimized for ethylguanidine, involving the endo- and exo- orientation of the lone NH and torsional angle χ6, as well as the torsional modes associated with χ4 and χ5. Torsional angle χ5 gives rise to s-cis and s-trans structures.Key words: ethylguanidine, ethylguanidinium ion, ab initio MO, arginine side-chain, conformational analysis.
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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 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.004 | 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".