Radical anion salts of 2,5-substituted N,N'-dicyanoquinonediimines (DCNQIs) with various counterions represent a new class of highly conducting organic materials. Among the copper salts of the DCNQIs (see figure) five new radical anion salts with stable metallic behavior are presented. A comparison of structural details with physical properties reveals their stable metallic state to be conserved by tight crystal packing, which is dependent on the size of the substituents on the DCNQIs.