Elektronentransfer und Ionenpaar-Bildung, 47 [1]. Titrationen von 1,2,4,5-Tetracyanbenzol und 7,7,8,8-Tetracyan-p-chinodimethan mit Natriummetall in aprotischen Lösungen
Electron transfer and ion pair formation, 47 [1]. Titrations of 1,2,4,5-tetracyanobenzene and 7,7,8,8-tetracyano-p-quinodimethane with sodium metal in aprotic solutions
- In an especially designed and sealed glass apparatus, a combination of UV/VIS and ESR spectroscopy measurements are performed to follow electron transfer reactions in aprotic (cH⊕ < 0,1 ppm) solution. For the sodium metal reductions of the tetracyano-substituted title compounds, the novel technique provides the following detailed information: 1,2,4,5- tetracyanobenzene is uniformly reduced to its radical anion, for which additional geometryoptimized MNDO calculations predict an already significant cyanine disortion. For 7,7,8,8- tetracyano-p-quinodimethane, UV/VIS band shape analysis allows to detect in the saturated THF reduction solution the 16300 cm-1 absorption of the donor/acceptor complex formed in the equilibrium TCNQ·⊖ + TCNQ ⇆ {TCNQ·⊖···TCNQ}, which according to a literature search has been crystallized and structurally characterized in paramagnetic salts such as [Me2⊕ (TCNQ·⊖)2(TCNQ)].
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