Synthesis and characterization of cationic iron complexes supported by the neutral ligands NP<sup><i>i</i>-Pr</sup><sub>3</sub>, NArP<sup><i>i</i>-Pr</sup><sub>3</sub>, and NS<sup><i>t</i>-Bu</sup><sub>3</sub>
Bibliographic record
Abstract
This paper compares the local geometries, spin states, and redox properties of a series of iron complexes supported by neutral, tetradentate NP3 (tris(phosphine)amine) and NS3 (tris(thioether)amine) ligands. Our consideration of an Fe-mediated N2 fixation scheme similar to that proposed by Chatt for molybdenum motivates our interest in systems of these types. This report specifically describes the synthesis and characterization of cationic Fe(II) chloride complexes supported by the neutral ligands NPi-Pr3 (NPi-Pr3 = [N(CH2CH2P-i-Pr2)3]), NArPi-Pr3 (NArPi-Pr3 = [N(2-diisopropylphosphine-4-methylphenyl)3]), and NSt-Bu3 (NSt-Bu3 = [N(CH2CH2S-t-Bu)3]). The solid-state structures, electrochemistry, and magnetic properties of these complexes are reported. Whereas the NPi-Pr3 and NArPi-Pr3 ligands provide pseudotetrahedral S = 2 ferrous cations [Fe(NPi-Pr3)Cl]PF6 (1[PF6]) and [Fe(NArPi-Pr3)Cl]BPh4 (2[BPh4]) featuring a long FeN bond distance, the NSt-Bu3 ligand gives rise to a trigonal bipyramidal structure with a S = 1 ground state and a much shorter FeN interaction. The complexes 1[BPh4] and 2[BPh4] can be reduced under CO to give rise to the five-coordinate Fe(I) monocarbonyls [Fe(NPi-Pr3)CO]BPh4 (4[BPh4]) and [Fe(NArPi-Pr3)CO]BPh4 (5[BPh4]). The solid-state structures and electrochemistry of 4[BPh4] and 5[BPh4] are described, as is the EPR spectrum of 4[BPh4]. The synthesis and characterization of the hydridedinitrogen complex [Fe(NPi-Pr3)(N2)(H)]PF6 (6[PF6]) has also been accomplished and its properties are also reported.Key words: nitrogenase, iron, polydentate phosphines, thioether ligands, N2 chemistry, nitrogen, Fe(I).
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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) | 0.000 | 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 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".