Samuel C. O'Neal

Solution chemistry of arsenic selenides: Synthesis, spectroscopy and the x-ray structures of [PPh4]2[AsnSe6], n = 2,4

Abstract As4Se4 and As4Se3 do not retain their solid-state structures in solution. Dissolution of As4Se4 in en/DMF (en = ethylenediamine, DMF = dimethylformamide) causes the cleavage of an AsAs bond and the formation of the As4Se62− anion. In the presence of excess polyselenide ions the remaining AsAs bond also breaks and the As2Se62− anion is produced. Reduction of As4Se4 by potassium in DMF in the presence of PPH4Cl also produces the As4Se62− anion. [PPh4]2[As4Se6] crystallizes (− 120°C) in the orthorhombic space group Pbca with cell dimensions a = 11.272(1), b = 19.817(2), c = 43.958(9) A, Z = 8. The As4Se62− anion resembles a basket with AsSe exocyclic bonds being the handles. [PPh4]2[As2Se6] crystallizes in the monoclinic space group P21/n with cell constants a = 10.817(2), b = 13.690(4), c = 16.298(3) A, β = 93.96(2)°, Z = 2. The As2Se62− ion has an As2Se4 ring in a trans-chair conformation with a terminal selenium atom on each arsenic atom.