Use of a cubane-type Mo 3CoS 4 molecular cluster as paramagnetic unit in the synthesis of hybrid charge-transfer salts

Abstract

Selective substitution of the chlorine atom coordinated to cobalt in the paramagnetic Mo 3(CoCl)S 4(dmpe) 3Cl 3 (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 [Mo 3(CoI)S 4(dmpe) 3Cl 3]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 Mo 3CoS 4 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 χ T 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.