PNN′ & P<sub>2</sub>NN′ ligands<i>via</i>reductive amination with phosphine aldehydes: synthesis and base-metal coordination chemistry
Bibliographic record
Abstract
Novel PNN' & P2NN' ligands based on 2-aminopyridine (APyPNN-R) R = Ph (1a), Cy (1b), iBu (1c), 8-aminoquinoline (AQPNN-R) R = Ph (2a), Cy (2b), iBu (2c), iPr (2d), and 2-picolylamine (P2NN-R) R = Ph (3a), Cy (3b), iBu (3c), have been synthesized via a versatile, one-pot, single-step, reductive amination of tertiary phosphine acetaldehydes with the amine by reaction with STAB (where STAB is sodium(triacetoxy)borohydride). Ligands 1b and 1c bridge between paramagnetic Co(ii) and form dimeric complexes Co2Cl4(APyPNN-R)2 (4 and 5) when reacted with cobalt dichloride. Ligands 2a-c coordinate in a tridentate fashion forming chelate complexes MCl2(AQPNN-R) M = Co(ii) (6-8), and, for 2d, the Fe(ii) complex FeCl2(AQPNN-iPr) (9). A solution magnetic susceptibility value for 9 of 3.9μB is consistent with a monomer-dimer equilibrium. The synthesis of the dimeric complex [FeCl2(AQPNN-Ph)]2 (10) using 2a as well as solid state magnetic susceptibility measurements on 9 and 10 confirm this phenomenon. Ligand 3a coordinates to Fe(ii) in an interesting tetradentate fashion despite bearing a tertiary amine moiety giving octahedral FeCl2(P2NN') (11). All of the metal complexes have been characterized by elemental analysis, paramagnetic 1H NMR spectroscopy, solution magnetic susceptibility, and single crystal X-ray diffraction (XRD).
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How this classification was reachedexpand
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 | 0.001 |
| 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 teacher head, 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".