Various extended π-donor molecules incorporating an azino spacer between two heterocyclic moieties, either dithiole or thiazole rings, are described. As evidenced by cyclic voltammetric studies, the donor ability of these derivatives can be modulated depending on the nature of the two heterocycles. Three similar crystalline complexes were obtained with TCNQ and the donors 4, 7 and 8. Crystal structures and magnetic susceptibility data of these complexes are presented and the degree of charge transfer within these complexes has been correlated with the redox properties.