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.

Oxidation of the 15 metal electron Mo3(CoCl)S4(dmpe)3Cl3 cluster causes selective substitution of the chlorine atom coordinated to cobalt to produce [Mo3(CoI)S4(dmpe)3Cl3]+ (1+) with 14 metal electrons and a S = 1 ground state. Combination of this magnetic cluster cation with square planar nickel dithiolate complexes affords charge-transfer salts.Figure optionsDownload as PowerPoint slide