Protonation-Induced Rank Failure of Quantum-Chemical Descriptors: A pH-Resolved Rank-Fidelity Framework in Matched Substituted Pyridines — Data and Code Package

This record contains the complete reproducibility package supporting the manuscript “Protonation-Induced Rank Failure of Quantum-Chemical Descriptors: A pH-Resolved Rank-Fidelity Framework in Matched Substituted Pyridines”. The study examines pH-dependent rank fidelity of quantum-chemical descriptors in a matched series of eleven substituted pyridines. Neutral and pyridine-ring-N-protonated states were calculated with ORCA 6.1.1 using a frozen B3LYP/G/6-31+G(d,p)/SMD(Water) protocol. Experimental conjugate-acid pKa values were used to generate Henderson–Hasselbalch populations over pH 2–12. Rank instability was evaluated from pairwise inversions among the 55 molecular pairs, exact pair-crossing analysis, descriptor-level perturbation-to-separation diagnostics, and Monte Carlo propagation of literature-informed pKa sensitivity. The archive contains the audited pKa input data, 44 canonical ORCA input files and associated calculation outputs, accepted geometries and Hessians, documented quality-control and repair history, extracted descriptor tables, pH-resolved rank-fidelity results, exact crossing and pairwise analyses, pKa-sensitivity results, reproducible analysis and figure-generation scripts, publication figures, Supporting Information, and software-environment metadata. The quantum-chemical protocol and analysis workflow are frozen for this release. Population-weighted cross-charge-state orbital energies and atomic charges are provided only as operational descriptors for comparative rank analysis and are not asserted to be unique quantum-mechanical observables of an equilibrium mixture. Data, figures, and documentation are distributed under CC BY 4.0. Source code is distributed under the MIT License; the corresponding license files are included in the archive. Release version: 1.0.