Bis(1-ethyl-3-methyl­imidazolium) 3,6-diselanyl­idene-1,2,4,5-tetra­selena-3,6-diphospha­cyclo­hexane-3,6-di­selen­olate

In the title compound, 2C₆H₁₁N₂⁺·P₂Se₈^2- or [EMIM]₂P₂Se₈ (EMIM = 1-ethyl-3-methyl­imidazolium), the anions, located about inversion centers between EMIM cations, exhibit a cyclo­hexane-like chair conformation. The cations are found in columns along the a axis, with centroid-centroid distances of 3.8399 (3) and 4.7530 (2) Å. The observed P-Se distances and Se-P-Se angles agree with other salts of this anion.