Cs2CuP3S9: A chiral compound with screw helices

The reaction of Cu with a molten mixture of Cs2S/P2S5 produced the quaterna ry compound Cs2CuP3S9. The bright yellow crystals of Cs2CuP3S9 are stable i n air and water for several weeks. The compound crystallizes in the chiral, hexagonal space group P6(5) (No. 170) and at 23 degrees C: a = 15.874(2) A ngstrom; c = 35.100(7) Angstrom; V= 7660(3) Angstrom(3); Z = 18, The [CuP3S 9](n)(2n-) chains are composed of an alternating arrangement of tetrahedral Cu+ ions and cyclic [P3S9](3-) units. The structure contains parallel heli cal [CuP3S9](n)(2n-) 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 therm al analysis, far-IR, Raman, and single-crystal optical transmission UV/vis spectroscopy. Positive nonlinear optical response and second harmonic gener ation response was observed. (C) 2000 Academic Press.