Room-temperature ferromagnetic behavior in 2,5-diethyltetracyanoquinodimethanide salts

The Li+ salts of radical anion of 2,5-diethyl-substituted TCNQ (DETCNQ) (Li+·DETCNQ−·) was converted to the corresponding NMe4+, PMe4+ and AsMe4+ salts, followed by recrystallization from CH3CN/Et2O to give single crystals of NMe4+·DETCNQ−·, PMe4+·DETCNQ−· and (AsMe4+·DETCNQ−·)·1/4DETCNQ, respectively, The crystal structure analyses showed that for NMe4+ and PMe4+ salts one-dimensional column composed of dimerized DETCNQ−· molecules is formed, while the two different DETCNQ−· stacks are uniform for the AsMe4+ salt. These DETCNQ−· salts also exhibited ferromagnetic behavior with very small saturation magnetization and coercive force, as was observed for the 1:2 mixed salts of TCNQ and 2,5-dimethyl-substituted TCNQ with their radical anions.