Stepwise Conversion from GeO2 to [MGe4S10]n3n- (M = Cu, Ag) Polymer via Isolatable [Ge2S6]4- and [Ge4S10]4- Anions by Virtue of Templating Technique.

Abstract

Rational synthesis of inorganic matter remains a great challenge encountered with modern synthetic chemistry. Here we reported the stepwise solvothermal conversion from GeO2 to [MGe4S10]n3n- (M = Cu, Ag) polymer via isolatable [Ge2S6]4- and [Ge4S10]4- anions by virtue of templating technique. The facile sulfuration of GeO2 resulted in the methylammonium-templated dimeric thiogermanate [CH3NH3]4Ge2S6 (1). This was used subsequently as a precursor for the formation of adamantane-like [Ge4S10]4- cluster, which was isolated as a mixed methylammonium/ethylammonium salt [CH3CH2NH3]3[CH3NH3]Ge4S10 (2). Compound 2 was then successfully used as a precursor to react with Cu+ and Ag+ cations in the presence of tetraethylammonium, resulting in alternating copolymeric products [(CH3CH2)4N]3MGe4S10 (M = Cu (3), Ag (4)), whose anionic moieties feature a novel zigzag chainlike structure constructed by [Ge4S10]4- clusters via two-coordinate Cu+/Ag+ linkers. Mixed amine/ethanol or deep eutectic solvents were applied as media for the syntheses of 1-4, and all the products were characterized in the solid state and solution. Crystal structural analysis of the title compounds revealed significant templating roles of the alkylammonium cations as both space-filling agents and hydrogen-bonding donors, suggesting the structure-directing mechanism for the species formation and crystal growth. The design and optimization of multistep structural conversion upon templating effects would be beneficial for drawing rational, predictable pathways for inorganic synthesis.