A relative stability scale of nitrogen donor ligand ruthenium complexes based on their stability constants calculated from first principles by DFT methods
Bibliographic record
Abstract
Using DFT calculations (M06/def2-TZVP/SMD solvent model) a relative stability scale is established from first principles for a series of iron and ruthenium complexes with ligand frameworks based on chelating pyridine- and pyrrole-type (porphyrin and phthalocyanine) ligands by determining the equilibrium constants for the complex formation reactions [M(H2O)6]2+ + nL → [M(L)n(H2O)m]2+ + (6 − m) H2O; M=Fe, Ru in aqueous solution through Hess's law and the van't Hoff equation. For a subset of the iron complexes, comparison against the available experimental data systematically underestimates the calculated constants by multiple orders of magnitude for the high-spin hexaaqua complex as the starting material, but shows a linear correlation trend between the experimental and calculated values. A similar correlation exists between the calculated values for the iron and ruthenium complexes. For the latter, for which no experimental data are available, the values are very high. On the relative scale calculated, the stability constants for the macrocyclic porphyrin and phthalocyanine complexes are unexpectedly low when calculated from the neutral ligand, but very high when calculated for reactions starting from the deprotonated ligand in its dianionic state. The limitations of the model are discussed, in particular with regards to the likely very large influence of solvation energies and hydrogen-bond networks not explicitly formulated in the SMD solvent model employed and Brønsted acid–base reactions between complexes and ligands, and its merits critically evaluated.
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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 | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.001 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.001 |
| Insufficient payload (model declined to judge) | 0.003 | 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".