A general structural principle for organic compounds that have the capacity for two-stage electron transfer is based on the following reaction sequence:X+CH=CHj,X 5 In this scheme one or both of the entities X may be replaced by Y'. The radical partners in these systems often have very high thermodynamic stability. The choice of the end groups X and Y, (partial) inclusion of n-systems in rings, alteration of the number of vinylene groups,

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Metallic conductivity that increases continuously up to 1.3 K and achieves values of over 500000 S cm−1 is exhibited by single crystals of the radical‐anion salt depicted here, which was prepared by electrocrystallization. The multidimensional electronic conductivity is discussed on the basis of the crystal structure. The CuI ions are arranged in chains, each of which is surrounded by four stacks of dicyanoquinonediimine radical anions (one negative charge per “dimer”).

The presence of diimine in solution can be shown conclusively by the stereospecific cishydrogenation of symmetrical multiple bonds. Apart from reactions which have hitherto been attributed to hydrazine, this review deals primarily with the various sources and secondary reactions of diimine.

Die 1,3-Dithiolderivate 8-11Red lassen sich zu den stabilen Radikalionen 8 -1 1~~~ oxidieren, deren Elektronen-und EPR-Spektren vermessen wurden. 8-11 bilden nach Red + Ox $ 2 Sem in Acetonitril ein reversibles zweistufiges Redoxsystem mit K = 106-107.Der EinfluR von Alkyl-und Benzo-Substitution wird diskutiert. Two Step Redox Systems, XI). -Tetrathioethylenes and their Higher Oxidation LevelsThe 1,3-dithiol derivatives 8-11Red form the stable radical cations 8 -1 1~~~ of which electronand ESR-spectra are obtained. According to Red + Ox 2 Sem, 8-11 form a reversible two-step redox system in acetonitrile with K = 106 -107. The influence of alkyl and benzo substitution is discussed. Bereits die Durchsicht der Literatur ergab, daB tetraaminosubstituierte khylene wie 26) und 37) recht stabile Radikalionen bilden, obwohl zumindest fur 2 eine Ver-* ) Korrespondenz bitte an diesen Autor richten.

A new class of quinone derivatives, the dicyanodiimines 2,21, and 23, has been synthesized by the reaction of the corresponding quinones with bis(trimethylsily1)carbodiimide (8) and titanium tetrachloride. A wide variety of substrates, even those which contain bulky groups and those which exhibit a strong influence on the redox potential, has been prepared. A route starting from p-phenylenediamines 4 via the N,N'-dicyanodiamines 6 has been found to be much more limited. The spectroscopic properties of compounds 2, 21, and 23 are discussed with respect to their synlanti isomerizations as well as substituent effects on their planarity. Mehrstufige reversible

Soweit bisher nicht bekannt, wird die Synthese der Diquartarsalze 3a-e, 3Ba-c und 4 sowie der zugehorigen Heterocyclen beschrieben. Diese Quartarsalze werden, zusammen mit 5a-c, polarographisch untersucht. Alle Verbindungen nehmen in Wasser, Acetonitril und D M F ein Elektron reversibel auf. Reversible Aufnahme eines zweiten Elektrons wird nur bei 3a, 3c und 4 beobachtet, jedoch nicht in Wasser. Die Semichinonbildungskonstanten liegen bei l o 5 bis 108. HMO-Berechnungen korrelieren gut mit dem N + V1-Ubergang, jedoch nicht mit dem Redoxpotential. Two-step Redox Systems, XU'). -Synthesis and Polarography of Quaternary Salts Derived from Phenanthrolines, 2,7-Diazapyrene and from DiazoniapentaphenesAs far as unknown the synthesis of the diquaternary salts 3a-e, 3Ba-c and4is described together with that of the parent heterocycles. Salts 3, 4 and 5a-c are investigated by polarography. In water, acetonitrile and DMF all compounds trap one electron reversibly. Reversible uptake of a second electron is observed with 3a, 3c and 4, however not in water. Semiquinone formation constants are 105 to 108. HMO calculations correlate well with N --f V1 transitions but not with redox potentials. A. ZielsetzungIm Rahmen der Untersuchung mehrstufiger Redoxsysteme vom Typ As) wurde in der vorangehenden Mitteilung 1) das klassische Weitzsche Diquartarsalz des 44'-Bipyridyls 1 a6) systematisch variiert : Die Pyridinringe wurden in verschiedenen Positionen verkniipft (1 ad) und diese Variation mit zwischengeschalteter khylenbriicke wiederholt (2a-f). Dabei zeigte sich, da13 nur solche Systeme reversibel zweistufig *) Korrespondenz bitte an diesen Autor richten. 1) XI. Mitteilung: S. Hiinig, J. GroJ und W. Schenk, Liebigs Ann. Chem. 1973, 324. 2) Die polarographischen Daten wurden bereits mitgeteilt: S. Hunig und J. GroJ, Tetra-3) Aus der Dissertation J. GroJ, Univ. Wurzburg 1968.

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