Donor-acceptor complex of a new bis-TTF donor containing a pyridine diester spacer with TCNQ as the acceptor: a disappointing system.

A new bis-TTF donor (TTF is tetrathiafulvalene) containing a pyridine diester spacer, namely bis{2-[(6,7-tetramethylene-3-methylsulfanyltetrathiafulvalen-2-yl)sulfanyl]ethyl} pyridine-2,6-dicarboxylate-tetracyanoquinodimethane-dichloromethane (2/1/2), 2C(33)H(33)NO(4)S(12) x C(12)H(4)N(4) x 2 CH(2)Cl(2), has been synthesized and its electron-donating ability determined by cyclic voltammetry. The electrical conductivity and crystal structure of this donor-acceptor (DA) complex with TCNQ (tetracyanoquinodimethane) as the acceptor are presented. The TCNQ moiety lies across a crystallographic inversion centre. In the crystal structure, TTF and TCNQ entities are arranged in alternate stacks; this feature, together with the bond lengths of the TCNQ molecule, suggest that the expected charge transfer has not occurred and that the D and A entities are in the neutral state, in agreement with the poor conductivity of the material (sigma(RT) = 2 x 10(-6) S cm(-1)).