Use of a cubane-type Mo3CoS4 molecular cluster as paramagnetic unit in the synthesis of hybrid charge-transfer salts

Selective substitution of the chlorine atom coordinated to cobalt in the paramagnetic Mo3(CoCl)S4(dmpe)3Cl3 (dmpe = 1,2-bis(dimethylphosphanyl) ethane) complex with a S = 1/2 ground state has been achieved by iodine oxidation to afford the also paramagnetic [Mo3(CoI)S4(dmpe)3Cl3]I ([1]I) salt with a S = 1 ground state in almost quantitative yield. Replacement of chorine by iodine has no significant effect on the structural and electrochemical properties of the Mo3CoS4 system. Metathesis of the [1]I salt with the paramagnetic nickel anionic dithiolate [Ni(mnt)2]− (mnt = maleonitrilodithiolate) affords [1]2[Ni(mnt)2]. The stoichiometry evidenced by X-ray analysis reveals that reduction of the [Ni(mnt)2]− radical to the corresponding diamagnetic closed shell [Ni(mnt)2]2− dianion, presumably via dismutation, has occurred during the metathesis process. The crystal structure of [1]2[Ni(mnt)2] consists of [Ni(mnt)2]2− dianions sandwiched by two cluster 1+ cations which yield {1+·[Ni(mnt)2]2−·1+} subunits arranged along the crystallographic c axis. Magnetic susceptibility measurements for [1]2[Ni(mnt)2] show a χT product of 0.99 emu K/mol largely unchanged in the 10–300 K range. This behavior agrees with the presence of an S = 1 cluster 1+ cation while the Ni(mnt)2 moiety does not contribute to the paramagnetism of the sample.