Conductivity and Magnetic Properties of the Charge-Transfer Complex from N,N'-Dicyanonaphthoquinonedimimine (DCNNI)and Tetrathiafulvalene (TTF)

Conductivity (dc and ac), ESR-properties and proton relaxation rates of the charge transfer complex Tetrathiafulvalene N,N′-dicyanonaphthoquinonediimine in the temperature range be­ tween 300 K and 3.8 K are reported. This salt belongs to the unusual group of organic conductors, in which segregated donor and acceptor stacks are associated in a pairwise manner. The physical properties, which are compared with TTF-TCNQ, give evidence of non-stoichiometric charge transfer (ρ ≠ 1). A metal like state can be identified for T> 70 K, as is seen from the weak temper­ ature dependence of the conductivity (σ ≈ 30 Scm ) and the susceptibility (X ≈ 7.5 ⋅ 10 emu/ mole) and from the Korringa like temperature dependence of the proton relaxation rates. The drop of the susceptibility at T ≈ 70 K and the activated temperature dependence of the conductivity for T < 70 K are explained by a metal-to-semiconductor transition.