Synthesis and spectroscopic (<sup>1</sup>H NMR, ESR) characterization of new aryloxy-Mn(II) complexes: steric control over <i>O</i>- vs. phenyl-π-coordination of ArO<sup>-</sup> ligands (ArO<sup>-</sup> = C<sub>6</sub>H<sub>5</sub>O<sup>-</sup>, 4-methyl-C<sub>6</sub>H<sub>4</sub>O<sup>-</sup>, 3,5-dimethyl-C<sub>6</sub>H<sub>3</sub>O<sup>-</sup>, 2,6-di-<i>tert</i>-butyl-C<sub>6</sub>H<sub>3</sub>O<sup>-</sup>, 2,6-dimethyl-C<sub>6</sub>H<sub>3</sub>O<sup>-</sup>) to the "Mn(II)Cp" moiety, and their reactivity with carbon dioxide
Bibliographic record
Abstract
The coordination chemistry of phenoxide ligands, such as C6H5O, 4-(CH3)-C6H4O, 3,5-(CH3)2-C6H3O, 2,6-(tert-butyl)2-C6H3O, 2,6-(CH3)2-C6H3O, to Mn(II) has been investigated because of the possible implication of Mn(II)phenoxide complexes as intermediates in the phenylphosphate carboxylase enzyme, a protein which catalyses the selective carboxylation of phenylphosphate to 4-OH-benzoic acid using CO2. We report here the synthesis and characterization of [CpMn(µ-OAr)(THF)]2 (ArO = C6H5O, 4-(CH3)-C6H4O, 3,5-(CH3)2-C6H3O, 2,6-(CH3)2-C6H3O) and [CpMn(η5-ArO)] (ArO = 2,6-(tert-butyl)2-C6H3O and 2,6-(CH3)2-C6H3O) complexes, the first examples of mixed-sandwich complexes with Cp and phenate as π-ligands. The latter bear the 2,6-substituted phenoxide π-coordinated to the [Mn(Cp)]+ moiety. The different mode of bonding of the phenoxide ligands to Mn(II), substantiated by 1H NMR and electron spin resonance (ESR) spectroscopy, is controlled by the steric hindrance of substituents at the 2- and 6-position. The reactivity of the π-bonded ligand towards CO2 is also reported as a quite rare example of nucleophilic attack at the cumulene by the ring-carbon of the phenoxide, which is driven by electron density localization at the 4-position generated upon π-coordination to Mn(II).Key words: Mn(II)-complexes, phenoxide ligands, 1H NMR spectroscopy, ESR spectroscopy, reaction with carbon dioxide.
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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".