The Spin Dependence of the Spatial Size of Fe(II) and of the Structure of Fe(II)-Porphyrins
Bibliographic record
Abstract
The question of why the iron displacement out of the porphyrin plane is enhanced in quintet states of singly ligated iron-porphyrin complexes compared to lower spin states and unligated iron-porphyrin is addressed. The spatial size of the Fe 2+ atom is analyzed with respect to different spin states, and it is shown that the ion size decreases with increasing spin state for the d 6 electronic configuration. This contradicts the common belief that the iron out-of-plane location in the quintet state of ligated Fe(II)-porphyrins is due to an increased required space of the iron within the porphyrin ring. Therefore, the singlet, triplet, and quintet ground states of imidazole-ligated iron-porphyrin have been calculated employing density functional theory, and the relevant molecular orbitals have been analyzed. Additional comparison with the unligated iron-porphyrin molecules reveals that the enhanced doming in the quintet state is the result of a combination of the weakening of the iron-ring nitrogen bonds by occupying antibonding orbitals and the repulsion between the imidazole ligand and the porphyrin ring.
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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 | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".