A Twin-TCNQ-Type Acceptor. Synthesis of 11,11,12,12,13,13,14,14-Octacyano-1,4:5,8-anthradiquinotetramethane and Structures of the Tetraethylammonium Salts of Its Mono- and Dianion

Article abstract of DOI:10.1246/bcsj.61.261

The title compound (OCNAQ)was synthesized.Treatment of 1,2,3,4,5,6,7,8-octahydroanthracene with N-bromosuccinimide (NBS) under irradiation using a 100-W light bulb in refluxing CCl4 followed by dicyanomethylation with excess of NaCH(CN)2 in Me2SO gave an isomeric mixture of 1,4,5,8-tetrakis(dicyanomethyl) derivatives.The mixture was subjected by repetition of the successive bromination-dehydrobromination procedure giving OCNAQ in 20percent overall yield.The cyclic voltammogram of OCNAQ exhibits four redox waves (E_1/2¹ 0.26, E_1/2² 0.05, E_1/2³ -0.44, and E_1/2⁴ -0.53 vs.SCE in MeCN), indicating that OCNAQ is a stronger acceptor than tetracyanoquinodimethane (TCNQ, E_1/2¹ 0.17 V vs.SCE).Both 1:1 and 2:1 salts, (Et4N)(OCNAQ) and (Et4N)2(OCNAQ), were obtained from reactions of Et4NI with potassium and lithium salts of OCNAQ, respectively.The X-ray crystal analyses of these salts indicate that the TCNQ moieties are boat-shaped bent to opposite directions.With the 1:1 slat, which behaves as a semiconductor (4E-4 Ω^-1 cm^-1 at room temperature, E_a 0.22 eV), the OCNAQ molecules are arrayed in the segregated stacking mode, while the 2:1 salt (E-7 Ω^-1 cm^-1) has no columnar structure of the OCNAQ molecules.