SOLUTION CHEMISTRY OF ARSENIC SELENIDES - SYNTHESIS, SPECTROSCOPY AND THE X-RAY STRUCTURES OF [PPH4]2[ASNSE6], N = 2,4

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-degrees-C) in the orthorhombic space group Pbca with cell dimensions a = 11.272(1), b = 19.817(2), c = 43.958(9) angstrom, 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 P2(1)/n with cell constants a = 10.817(2), b = 13.690(4), c = 16.298(3) angstrom 93.96(2)-degrees, Z = 2. The AS2Se62- ion has an AS2Se4 ring in a trans-chair conformation with a terminal selenium atom on each arsenic atom.