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–

Abstract

Four new nickel thiophosphate anions have been isolated as 1-ethyl-3-methylimidazolium (EMIM) salts: [EMIM](2)[Ni(P(2)S(8))(2)] (1), [EMIM](3)[Ni(P(3)S(9))(P(2)S(8))] (2), [EMIM](4)[Ni(P(3)S(9))(2)] (3), and [EMIM](7)[(NiP(3)S(8))(4)(PS(4))] (4). Single crystals of each were prepared by ionothermal reaction of the elements in [EMIM][BF(4)]. 1 can also be obtained from [EMIM][CF(3)SO(3)]. 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-P(2)S(8)(2-) ligands are cis to each other. The anion in 2 contains two different tridentate thiophosphate ligands, 1,3-P(2)S(8)(2-) and P(3)S(9)(3-), whereas the anion in 3 consists of two P(3)S(9)(3-) ligands coordinated to the central Ni atom. The anion in 4 is complex, consisting of four NiP(3)S(8)(-) clusters surrounding a central PS(4) tetrahedron; within the NiP(3)S(8)(-) 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.