The intermolecular contacts between chalcogen atoms and cyano lone pairs were found to stabilize the crystalline state by electrostatic interaction. This interaction is one of the sources of the directionality in crystal packing of organic molecules and causes the formation of various types of inclusion lattices in the charge-transfer (CT) crystals of 1-3. By using highly selective formation of CT crystals with substituted aromatic hydrocarbons, particular isomers such as p-xylene or 2,6-dimethylnaphthalene (2,6-DMN) could be separated from the corresponding isomer mixtures. Lattice-related interaction plays a more significant role than molecular orbital interaction in the observed selectivity for para-disubstituted benzenes. However,

No abstract

No abstract

Bis[l,2,5]thiadiazolo-tetracyanoquinodimethane (1) was prepared and found to form a highly conductive complex with tetrathianaphthacene.

Anion radical salts of bis[1,2,5]thiadiazolotetracyanoquinodimethan (BTDA) containing forty kinds of alkylammonium ions were prepared whose molar ratios are unique for each cation and changed from 1:1 (2A–2L) to 2:3 (2M–2Z), 1:2 (2a–2m), and 2:5 (2n) with elongation of the side chains. The electrical conductivities of the salts are largely affected by the molar ratio and the spatial requirement of cations (ρRT 3.1 Ω cm for 2a and 4.2×106 Ω cm for 2L), and some of the salts exhibit high electrical conductivities (ρRT 3.1–8.3 Ω cm for 2a–2e) with small anisotropy (ρ⁄⁄ 1.7 Ω cm, ρ⊥ 21.6 Ω cm for a single crystal of 2g). Three salts (2A, 2M, and 2g) showed semiconducting temperature dependence of electrical conductivity with the activation energies of 0.12–0.20 eV. The X-ray study of three kinds of the salts (2A, 2g, and 2m) revealed that two-dimensional networks are formed by S–N≡C interactions (3.12–3.33 Å) of BTDA anion radicals. The crystals of 2A and 2g showing higher conductivities consist of two-dimensionally expanded “ribbon” networks accompanied with equally spaced columnar stackings while molecules are pairing to form dyads in 2m which exhibits lower conductivity.