Charge-transfer salts of M(mnt)2 (M = Ni, Pd, Pt, Au) with BDNT:: Ferromagnetic interactions in conductive (BDNT)2-[Ni(mnt)2]

Charge-transfer salts between BDNT and M (mnt)(2) (M = Ni, Pd, Pt, and Au) have been prepared by mixing BDNT-(SbCl6)(2) and (TBA)(2)-[M(mnt)(2)] and by electrochemical oxidation of BDNT in TBA-[M(mnt)(2)] solution. Almost all powdery samples of (1:1) salts show high electrical conductivity. The valence of M (mnt)(2) was determined; to be -1 by the CN stretching mode, which means that the valence of BDNT is + 0.5, + 1, or + 2. Their crystal structures are not known except for the low-conductive BDNT-[Au(mnt)(2)](2), in which Au(mnt)(2) forms dimers which are arranged in crisscross stacks, Among these compounds, (BDNT)(2)-[Ni(mnt)(2)] exhibits a ferromagnetic interaction with \ J \ = 3.4 K. It is concluded from the EPR experiment that[Ni(mnt)(2)](-) is responsible for the ferromagnetic interaction.