Tetraphenylphosphonium-tetraiodotrithiotriarsenat,PPh4[As3S3I4]

Tetraphenylphosphonium tetraiodotrithiotriarsenate, PPh₄As₃S₃I₄] PPh₄As₃S₃I₄] is formed along with PPh₄I₃ and other unidentified compounds by the reaction of As₂S₃, PPh₄I and HI in CH₂I₂ at 80°C. PPh₄As₃S₃I₄] was characterized by its IR spectrum and an X-ray crystal structure determination (3684 unique observed reflexions, R = 0.083). Crystal data: a = 1390.3, b = 1548.9, c = 1505.4 pm, β = 91.08°, monoclinic, P2₁/c, Z = 4. The crystals are not isotypic with the corresponding chloro and bromo compounds, although the anion constitutions are of the same type. The As₃S₃I₄]^? ion consists of an As₃S₃ ring in the chair conformation, the three As atoms are commonly linked to a bridging I atom and each As atom is bonded to one terminal I atom. Cations and anions are packed in alternating layers.