Density Functional Theory Analysis of Stereoelectronic Properties of Cobalamins
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Bibliographic record
Abstract
Density functional theory (DFT) is applied to the calculation of the steric and electronic factors which might affect the Co−C R bond activation in coenzyme B 12 . The six-coordinate cobalamins (B−[Co III (corrin)]−R, models of coenzyme B 12 ) include the actual corrin macroring as the equatorial ligand and imidazole (Im), dimethylbenzimidazole (DBI) or water (H 2 O), as the α-trans ligand (B). The β axial ligand (R) represents a series of alkyl groups with different steric bulkiness ranging from −C⋮N, −C⋮CH through methyl, ethyl, isopropyl, tert -butyl to 5‘-deoxy-5‘-adenosyl. Each trans ligand (Im, DBI or H 2 O) produces a positive correlation of the Co−C R and Co−N B bond lengths. The increasing complexity of the R group leads to two major structural correlations: a positive correlation between the Co−C R and Co−N B bond lengths and an inverse correlation between the Co−C R bond length and the flatness of the corrin ring. It is shown that stereoelectronic properties of cobalamins can only be explained on the basis of electronic considerations. Moreover, electron donation from axial ligands to the cobalt atom either by electron donating substituents or by a properly oriented external electric field caused by external electric charges is argued to be the main trigger for the activation of the Co−C R bond.
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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 | 0.000 |
| 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 it