A new series of salts, the (DMCTTF)₂X, has been recently synthesised. These compounds have already been characterised through electrical conductivity and ESR measurements. The authors summarise this study and present additional results for sulphur compounds with tetrahedral anions. New crystallographic data, transfer-integral calculations and electronic properties in the paramagnetic state are presented. These compounds are characterised by the presence of two organic layers in the unit cell. Moreover, an antiferromagnetic ordering is found for both layers. Thus, they also describe antiferromagnetic resonance data obtained with an X-band spectrometer below the Neel temperature. Finally, they employ these results in discussing the interactions relevant for AF ordering. In particular, they analyse the magnetic anisotropy and the role of the inter-layer interactions.