Solvothermal synthesis of three new dimeric thiogermanates (enH)4Ge2S6, [Mn(en)3]2Ge2S6 and [Ni(en)3]2Ge2S6 from germanium dioxide and sulfur powder

Three new thiogermanates (enH)4Ge2S6 (1) and [M(en)3]2Ge2S6 (M=Mn (2), Ni (3); en=ethylenediamine) were synthesized using GeO2 and S8 as starting materials in molar ratio of 1:0.5 under solvothermal conditions. These compounds suggest that the dimeric [Ge2S6]4− anion is likely to be the main germanium-containing species in en system and it also might be preferred as counter anions by the transition metal complex cations in crystallization. The cations of [Mn(en)3]2+ and [Ni(en)3]2+ are even better mineralizers than the protonated amine of [enH]+. The crystal systems of [Ge2S6]4− compounds are related to entities of cations and intermolecular reactions between cations and [Ge2S6]4− anions. The compounds remove ethylenediamine and H2S molecules in multi steps when being heated under nitrogen stream.