Hexacyano radialene

In contrast to 51, hexacyano[3]radialene (50) proved difficult to obtain in pure form. Freshly prepared samples are bright-yellow, but mm brown on exposure to air and blue on contact with many solvents. Potassium bromide and sodium iodide reduce 50 to the radical anion and the dianion, respectively24. 

Hexacyano[3]radialene (50) is a very powerful electron acceptor according to both experiment23,24 35 and MNDO calculations of LUMO energy and adiabatic electron affinity25. The easy reduction to the stable species 50" and 502- by KBr and Nal, respectively, has already been mentioned. Similarly, the hexaester 51 is reduced to 512-by Lil24. Most [3]radialenes with two or three quinoid substituents are reduced in two subsequent, well-separated, reversible one-electron steps. As an exception, an apparent two-electron reduction occurs for 4620. The reduction potentials of some [3]radialenes of this type, as determined by cyclic voltammetry, are collected in Table 1. Due to the occurrence of the first reduction step at relatively high potential, all these radialenes... 

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