Cs2CuP3S9: A Chiral Compound with Screw Helices

The reaction of Cu with a molten mixture of Cs2S/P2S5 produced the quaternary compound Cs2CuP3S9. The bright yellow crystals of Cs2CuP3S9 are stable in air and water for several weeks. The compound crystallizes in the chiral, hexagonal space group P65 (No. 170) and at 23°C: a=15.874(2) ?; c=35.100(7) ?; V=7660(3) ?3; Z=18. The [CuP3S9]2n-n chains are composed of an alternating arrangement of tetrahedral Cu+ ions and cyclic [P3S9]3- units. The structure contains parallel helical [CuP3S9]2n-n chains that run along the c-axis. The cyclic [P3S9]3- unit derives from the molecular adamantane [P4S10] unit with one [PS]3+ vertex removed. The title compound was characterized by differential thermal analysis, far-IR, Raman, and singlecrystal optical transmission UV/vis spectroscopy. Positive nonlinear optical response and second harmonic generation response was observed.