Electrochemical and Electronic Structure Investigations of the [S₃N₃]^•Radical and Kinetic Modeling of the [S₄N₄]ⁿ/[S₃N₃]ⁿ(n= 0, −1) Interconversion

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 , 1.17Â10 -5 cm 2 s -1 ; [S 3 N 3 ] -, 4.00 Â 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 °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 constantwas 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 ] • .

Structural Changes Upon Oxidation of (PtBu2)2 and 1,4‐(CH2)2(PtBu)4: Transannular P–P Interactions in Cations of the 1,4‐C2P4 Ring

“…A spectroelectrochemical study was undertaken using an in situ EPR‐voltammetry approach to look for confirmation of one‐electron processes in the voltammetry of 1 and 2 . For this study, we employed the miniaturized simultaneous electrochemistry electron paramagnetic resonance (SEEPR) cell with a gold micromesh working electrode described previously . Working at 0°C within the quartz Dewar insert of a TM 110 resonator at X‐band, a weak signal could be detected for 2 when electrolysis was conducted at E p a1 , while similar attempts for 1 at E p a1 were unsuccessful in detecting any signal; these results are consistent with the relative lifetimes of the radical cations displayed in the CV studies.…”

Open-shell doublet character in a hexaazatrinaphthylene trianion complex

“…This observation indicates that • radical. 34 In addition to the similarities in their open-shell doublet nature, organic triradicals are characterized by their highly reactive nature, which means that the experimental systems tend to be studied using matrix isolation techniques at cryogenic temperatures, or via gas-phase mass spectrometry.…”

Isomere des Dischwefeldinitrids, S2N2

“…Photolyse mit Nah-UV-LEDLicht (l max % 405 nm) baut diese Bande ab und bildet dafür N 2 S (C 1v ). DFT-Rechnungen sagen voraus, dass die Bildung von Triplett-trans-SNNS (C 2h , 3 A u ) aus der gewinkelten SNSN-Spezies über einen cyclischen Übergangszustand mit niedrigerer Energie (178 kJ mol À1 ) erfolgt, als der Strahlungsenergie von l = 520 nm 230 kJ mol À1 entspricht (Abbildung S4). Berechnete IR-Daten für dieses N-N-gebundene [a] beobachtet [b] berechnet [a] beobachtet [b] berechnet [a] beobachtet [b] n i n i Dn( 15 N) [b] n i n i Dn( 15 N) [b] n i n i Dn( 15 N) [b] 1654.2 (sw) [d] Zusammenfassend kann festgestellt werden, dass die experimentellen Ergebnisse einen Einblick in die komplexe PES von S 2 N 2 ermçglichten.…”

“…Dagegen ließen sich zwei neue gewinkelte Triplett-SNSN und ein neues cyclisches (SN) 2 zum ersten Mal nachweisen, und die Bildung von Triplett-trans-SNNS (C 2h , 3 A u ) durch Photolyse von matrixisoliertem SNSN wurde vorgeschlagen. Die vorliegende Studie weitet die bekannte Chemie von S 2 N 2 aus und trägt zu aktuellen Arbeiten zur Aufklärung des Mechanismus der Festkçrperpolymerisation von cyclischem S 2 N 2 (a) bei, an der offenschalige SNSN-Isomere beteiligt sein sollen.…”