Cyclometalated Ru Complexes of Type [Ru<sup>II</sup>(<i>N<sup>∧</sup>N</i>)<sub>2</sub>(<i>C<sup>∧</sup>N</i>)]<sup><i>z</i></sup>: Physicochemical Response to Substituents Installed on the Anionic Ligand
Bibliographic record
Abstract
The electrochemical and photophysical properties of a series of Ru(II) complexes related to [Ru(dcbpyH(2))(2)(ppy)](1+) (1; dcbpyH(2) = 4,4'-dicarboxy-2,2'-bipyridine; ppy = 2-phenylpyridine) were examined to elucidate the effect of modifying the anionic fragment of the C--N ligand with conjugated substituents (R). Included in this study is a family of compounds (2-5) consisting of one or two -NO(2) groups installed meta, ortho, and para to the organometallic bond. A suite of compounds with electron-donating and withdrawing groups (e.g., R = -F (6), -phenyl (7), -4-pyridine (8), -thiophene-2-carbaldehyde (9)) were also evaluated. Deprotonated forms of select compounds were isolated as tetrabutylammonium salts to benefit solution studies. All complexes were structurally characterized by a combination of mass spectrometry, (1)H and (13)C NMR spectroscopy, and/or elemental analysis. The electronic absorption spectra for all of the compounds reveal three broad bands over the 350-700 nm range. The maximum wavelength of the lowest energy absorbance bands for complexes modified with electron-withdrawing groups are hypsochromically shifted up to 45 nm relative to 1; the weakly emitting compounds (i.e., 1, 3, 6-9) display a hypsochromic shift of up to 63 nm compared to 1. Emission was not observed in cases where the -NO(2) group was positioned meta to the Ru-C bond. The sensitivity of the oxidation potentials to the nature, number, and position of the electron-withdrawing/-donating substituents for the entire set of compounds reflect a highest occupied molecular orbital (HOMO) character extended over the metal, the anionic portion of the C--N ligand, and, in the case of 7-9, the conjugated R group. The reduction potentials indicate that the lowest unoccupied molecular orbital (LUMO) is localized to the C--N ligand where R = -NO(2), and on the dcbpyH(2) ligands for all other compounds. This assessment was corroborated by time-dependent density functional theory (TD-DFT) studies.
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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".