This article presents the single-crystal structure of the complex salt sodium dithiocuprate(I) dodecahydrate Na₃CuS₂·12(H₂O), i.e., [Na₃(H₂O)₁₂][CuS₂], which forms in the high-sulfide concentrations of the alkaline solutions used for arsenic separation from copper concentrates. It features a linear hydrogen-bonded dithiocuprate(I) anion, a novelty in crystallographically characterized thiocuprates. During the study of the alkaline sulfide leaching of Chilean copper concentrates, an analytical investigation of the solution led to the detection of this complex. This study aimed to understand the chemical behavior of the leaching solution by identifying existing ions, which facilitated the discovery of the complex using single-crystal analysis. The newly discovered complex was also synthesized from a modeling solution based on the leaching solution recipe for arsenic removal, allowing for further crystal characterization through Raman and XRD analysis. By estimating the sodium sulfide threshold concentration that enhanced the formation of the copper disulfide complex, this study defined the upper technical threshold limit of sulfide concentration for the economic development of alkaline sulfide leaching to remove arsenic.

Several Co(III) ammine coordination compounds (chloride, sulfate, nitrate, and oxalate) were synthesized and characterized using single‐crystal X‐ray diffraction, Raman spectroscopy, elemental analysis, and thermal analysis. Here, we present five new crystal structures of cobalt coordination compounds and discuss them in the context of other related structures. Raman spectroscopy provides complementary symmetry and structural information via detailed band assignments. These fundamental data contribute to a deeper understanding of coordination compounds in which cobalt is stabilized in the trivalent oxidation state. Such insight is essential for assessing these compounds as structurally well‐defined precursor intermediates in the synthesis of electrode materials for lithium‐ion batteries.