Ionothermal Synthesis of Four New Nickel Thiophosphate Anions: [Ni(P2S8)2]2–, [Ni(P3S9)(P2S8)]3–, [Ni(P3S9)2]4–, and [(NiP3S8)4(PS4)]7

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-P2S8 2– ligands are cis to each other. The anion in 2 contains two different tridentate thiophosphate ligands, 1,3-P2S8 2– and P3S9 3–, whereas the anion in 3 consists of two P3S9 3– 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.