The Effect of Multiplicity on the Size of Iron(II) and the Structure of Iron(II) Porphyrins
Bibliographic record
Abstract
The displacement of the iron(II) atom from the porphyrin plane in iron(II) porphyrin complexes is investigated with respect to the spin state of iron(II) employing density functional theory. In this study the quantum theory of atoms in molecules (QTAIM) is used to show that the atomic volume of iron is smaller in the quintet state of imidazolium ligated iron(II) porphyrin than in the triplet state. This is consistent with what has been found for free atoms and contradicts the original interpretation of structural studies with X-rays, which assumed that the out-of-plane displacement of iron from the porphyrin ring in the quintet state is due to the increased spatial size of the high-spin iron atom. The bonding environment of the iron atom is analyzed with respect to the electron density (ρ) at the bond critical points (BCPs). It is found that in the quintet state, relative to the triplet state, there is a stronger bonding interaction between iron and the nitrogen atoms of the porphyrin despite a longer bond length. It has previously been suggested that the weakening of these bonds is the cause of the out-of-plane displacement of iron. Since this is not the case, this implies that the magnitude of the bonding interaction between the iron atom and the axial ligand has a more significant role in the domed structure of the quintet state.
Fetched live from OpenAlex and de-inverted. Abstracts are not stored in this database: the inverted indexes are 8.6 GB of the frame’s 9.3 GB of text, and the host has 13 GB free.
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 | 0.002 |
| 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) | 0.002 | 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".