Electrochemical and Electronic Structure Investigations of the [S<sub>3</sub>N<sub>3</sub>]<sup>•</sup>Radical and Kinetic Modeling of the [S<sub>4</sub>N<sub>4</sub>]<sup><i>n</i></sup>/[S<sub>3</sub>N<sub>3</sub>]<sup><i>n</i></sup>(<i>n</i>= 0, −1) Interconversion
Bibliographic record
Abstract
Voltammetric studies of S(4)N(4) employing both cyclic (CV) and rotating disk (RDE) methods in CH(2)Cl(2) at a glassy carbon electrode reveal a one-electron reduction at -1.00 V (versus ferrocene/ferrocenium), which produces a second redox couple at -0.33 V, confirmed to be the electrochemically generated [S(3)N(3)](-) by CV studies on its salts. Diffusion coefficients (CH(2)Cl(2)/0.4 M [(n)Bu(4)N][PF(6)]) estimated by RDE methods: S(4)N(4), 1.17 x 10(-5) cm(2) s(-1); [S(3)N(3)](-), 4.00 x 10(-6) cm(2) s(-1). Digital simulations of the CVs detected slow rates of electron transfer for both couples and allowed for a determination of rate constants for homogeneous chemical reaction steps subsequent to electron transfer. The common parameters (k(f1) = 2.0 +/- 0.5 s(-1), k(s1) = 0.034 +/- 0.004 cm s(-1) for [S(4)N(4)](-/0); k(f2) = 0.4 +/- 0.2 s(-1), k(s2) = 0.022 +/- 0.005 cm s(-1) for [S(3)N(3)](-/0) at T = 21 +/- 2 degrees C) fit well to a "square-scheme" mechanism over the entire range of data with first order decay of both redox products. An alternate model could also be fit wherein [NS](*) liberated in the first step reacts with formed [S(3)N(3)](*) to reproduce S(4)N(4) with an apparent second order rate constant k(f2)' = 1.1 +/- 0.3 x 10(3) M(-1) s(-1). The crystal structure of [PPN][S(3)N(3)] was determined by X-ray crystallography indicating the solvation of the anion by 1 equiv of methanol. The generated [S(4)N(4)](-*) radical anion was detected by the Simultaneous Electrochemical Electron Paramagnetic Resonance (SEEPR) method to give: (a) [(32)S(4)(14)N(4)](-*), 9 lines, a((14)N) = 0.118 mT; (b) [(32)S(4)(15)N(4)](-*), 5 lines, a((15)N) = 0.164 mT; (c) [(33)S(4)(14)N(4)](-*), estimated a((14)N) = 0.118, a((33)S = 0.2 mT); g = 2.0008(1). Equivalence of (33)S hyperfine splittings is consistent with dynamic averaging of the C(2v) geometry in solution. High-level electronic structure calculations provide evidence for an open-shell doublet triradicaloid character to the ground state wave function of [S(3)N(3)](*).
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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) | 0.002 | 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".