Toward Binary Nitrosyls: Distinctly Bent Fe−N−O Linkages in Base-Stabilized Fe(NO)<sub>3</sub><sup>+</sup> Complexes
Bibliographic record
Abstract
Air- and moisture-sensitive Fe(NO)(3)(eta(1)-PF(6)) (1) may be conveniently prepared by treating Fe(NO)(3)Cl with 1 equiv of [Ag][PF(6)] in CH(2)Cl(2) or by reacting [NO][PF(6)] with excess iron filings in MeNO(2). Complex 1 is thermally sensitive both as a solid and in solutions, and is best handled below -20 degrees C. To isolate 1 reproducibly from MeNO(2) solutions it is necessary to remove all traces of propionitrile, which often occurs as an impurity in MeNO(2), because it reacts with Lewis-acidic 1 to form [Fe(NO)(3)(EtCN)][PF(6)] (2). If trace H(2)O is present during the synthesis of 1, some of the PF(6)(-) is converted to PO(2)F(2)(-), which is sufficiently Lewis basic that it captures two Fe(NO)(3)(+) fragments and forms [(ON)(3)Fe(mu-PO(2)F(2))Fe(NO)(3)][PF(6)] (3). Finally, Fe(NO)(3)(eta(1)-BF(4)) (4) can be obtained as a green microcrystalline powder by employing the same synthetic methodologies used to prepare 1. The new complexes 1-4 have been characterized by conventional spectroscopic methods, and the solid-state molecular structures of 2, 3, and 4 and their parent compound, Fe(NO)(3)Cl, have been established by X-ray diffraction methods. The iron centers in the Fe(NO)(3) fragments in all these structures exhibit approximately tetrahedral coordination geometries, and the Fe-N-O linkages are distinctly nonlinear with bond angles in the range of 159 to 169 degrees. DFT calculations on Fe(NO)(3)(eta(1)-BF(4)) (4) confirm that its bent Fe-N-O links have an electronic origin and need not be attributed to other factors, such as packing forces in the crystal. Interestingly, the bending of the NO ligands results in an increase in the energy of the HOMO, relative to the linear case, but at the same time causes a decrease in energy of the HOMO-1 and the HOMO-2 molecular orbitals. This more than compensates for the higher energy of the HOMO, resulting in a lower energy structure.
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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".