Ionothermal Synthesis of Four New Nickel Thiophosphate Anions: [Ni(P₂S₈)₂]^2–, [Ni(P₃S₉)(P₂S₈)]^3–, [Ni(P₃S₉)₂]^4–, and [(NiP₃S₈)<sub>4</

Four new nickel thiophosphate anions have been isolated as 1-ethyl-3-methylimidazolium (EMIM) salts: [EMIM]2[Ni­(P2S8)2] (1), [EMIM]3[Ni­(P3S9)­(P2S8)] (2), [EMIM]4[Ni­(P3S9)2] (3), and [EMIM]7[(NiP3S8)4(PS4)] (4). Single crystals of each were prepared by ionothermal reaction of the elements in [EMIM]­[BF4]. 1 can also be obtained from [EMIM]­[CF3SO3]. In all four anions, Ni atoms are octahedrally coordinated and P atoms are tetrahedrally coordinated. In the anion found in 1, two tridentate 1,3-P2S82– ligands are cis to each other. The anion in 2 contains two different tridentate thiophosphate ligands, 1,3-P2S82– and P3S93–, whereas the anion in 3 consists of two P3S93– ligands coordinated to the central Ni atom. The anion in 4 is complex, consisting of four NiP3S8– clusters surrounding a central PS4 tetrahedron; within the NiP3S8– groups, one P atom is directly bound to Ni. The discovery of these four new compounds demonstrates the versatility of ionothermal methods for the synthesis of novel thiophosphates.