Preparation and Properties of Pyridine-Analogue of TCNQ Dianion Salt

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Abstract
Bis(tetrapropyl- and tetrabutylammonium) 1,1′-(2,5-pyridinediyl)bis[dicyanomethanide] (4a and 4b) were prepared in order to investigate the properties of pyridine-analogue 3 of TCNQ as a new electron acceptor and its complexation with TTF. Although 3 was not isolated, the cyclic voltammetry of the salt 4 indicated that 3 was a stronger electron acceptor than TCNQ. The charge-transfer complex of TTF and 3 was prepared by mixing TTF with 3 which was generated in situ from the electrolytic oxidation of 4 or from the oxidation of 2,5-bis(dicyanomethyl)pyridine, a precursor of 4, with hydrogen peroxide. It consisted of 1 : 1 composition of donor and acceptor and showed a high electrical conductivity of 19 S cm−1. The 2 : 1 complex was prepared by metathesis of (TTF)3(BF4)2 and 4, and also highly conductive.