Mono- and Dinuclear Complexes of Chiral Tri- and Tetradentate Schiff-Base Ligands Derived from 1,1‘-Binaphthyl-2,2‘-diamine
Bibliographic record
Abstract
The synthesis and characterization of the bis(bidentate) Schiff-base ligand [(R)-2] formed by the condensation reaction of (R)-1,1'-binaphthyl-2,2'-diamine [(R)-BINAM] with pyridine-2-carboxaldehyde is presented. The coordination chemistry of (R)-2 with Ni(ClO(4))(2).6H(2)O, Co(ClO(4))(2).6H(2)O, CuCl(2), and CuSO(4) has been investigated. Reaction of (R)-2 with the first two metal salts leads to complexes of the type [M((R)-4)(2)](ClO(4))(2) (M = Ni(II), Co(II)), where (R)-4 is a tridentate ligand resulting from the hydrolytic cleavage of one of the pyridyl groups from (R)-2. Both complexes were characterized by X-ray crystallography, which showed that the Lambda absolute configuration of the metal center is favored in both cases. (1)H NMR spectroscopy suggests that the high diastereoselectivity of Lambda-[Co((R)-4)(2)](ClO(4))(2) is maintained in solution. The reaction of (R)-2 with CuCl(2) leads to the dinuclear complex [Cu(2)((R)-2)Cl(4)], which has a [Cu(2)(mu(2)-Cl(2))] core. The reaction of CuSO(4) with (R)-2 gives a dimeric complex, [Cu((R)-4)SO(4)](2), which features a [Cu(2)(mu(2)-(SO(4))(2))] core. This complex can be prepared directly by the reaction of (R)-BINAM with pyridine-2-carboxaldehyde and CuSO(4). The use of rac-BINAM in this synthetic procedure leads to the heterochiral dimer [Cu(2)((R)-4)((S)-4)(SO(4))(2)]; that is, the ligands undergo a self-sorting (self/nonself discrimination) process based on chirality. The reaction of rac-BINAM, pyridine-2-carboxaldehyde, and Co(ClO(4))(2).6H(2)O proceeds via a homochiral self-sorting pathway to produce a racemic mixture of [Co((R)-4)(2)](2+) and [Co((S)-4)(2)](2+). The variable-temperature magnetic susceptibilities of the bimetallic complexes [Cu(2)((R)-2)Cl(4)], [Cu((R)-4)(mu(2)-SO(4))](2), and [Cu(2)((R)-4)((S)-4)(mu(2)-SO(4))(2)] all show weak antiferromagnetic coupling with J = -1.0, -0.40, and -0.67 cm(-)(1), respectively.
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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 | 0.001 | 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".