2 CONDUCTIVE PHASES OF 1,3-DIMETHYLIMIDAZOLIUM-(TCNQ)(2) COMPLEX SALT

Two conductive phases were found by crystallization of the complex ion -radical salt of the 1,3-dimethylimidazolium 7,7',8,8'-tetracyano-1,4- quinodimethane (TCNQ) under different conditions: (i) bulk crystalliza tion from the acetonitrile solution and (ii) crystallization on a glas s substrate giving rise to an interconnected fibrous crystal conductiv e network (sigma = 1.7 mS square(-1)). The electrical conductivity of the latter phase is more than four orders of magnitude higher than tha t of the former phase. The crystal lattices of both phases are differe nt. The first phase is triclinia (P1) with cell parameters a = 7.811 A ngstrom, b = 13.378 Angstrom, c = 7.276 Angstrom, alpha = 93.152 degre es, beta = 113.739 degrees, gamma = 106.068 degrees. Indexing of the X -ray diffraction patterns recorded with samples of the latter phase gi ves a = 13.65 Angstrom, b = 12.70 Angstrom, c = 3.80 Angstrom, gamma = 108.3 degrees; alpha and beta could not be determined.