K4In2(PSe5)2(P2Se6) and Rb3Sn(PSe5)(P2Se6):: One-dimensional compounds with mixed selenophosphate anions

The reaction of In with a molten mixture of K2Se/P2Se5/Se yielded brick-red, needle-like crystals of K4In2(PSe5)(2)(P2Se6). The reaction of Sn with a molten mixture of Rb2Se/P2Se5/Se yielded black plate-like crystals of Rb3Sn(PSe5)(P2Se6). Both compounds are stable in air and water. K4In2(PSe5)(2)(P2Se6) crystallizes in the monoclinic space group Cc (9) with a= 11.1564(1) Angstrom, b=22.8771(1) Angstrom, c=12.6525(2) Angstrom, beta=109.039 (1)degrees, Z=4, and R/R-w=4.1/4.4%. The one-dimensional structure features [In-2(PSe5)(2)(P2Se6)](n)(4n-) chains that consist of In-2(PSe5)(2) dimers. These dimers are then bridged along the a-axis by tetradentate [P2Se6](4-) units to form the chain. In3+ is in an octahedral environment. Rb3Sn(PSe5)(P2Se6) crystallizes in the monoclinic space group P2(1)/a (14) with a=14.013(2) Angstrom, b=7.3436(8) Angstrom, c=21.983(4) Angstrom, beta=106.61(1)degrees, Z=4, and R/R-w= 3.5/4.4%. The one-dimensional structure features [Sn(PSe5) (P2Se6)](n)(3n-) chains with octahedral Sn4+. The neighboring Sn atoms are connected via tetradentate [P2Se6](4-) units to form the chain. The [PSe5](3-) act as chelating side groups employing the diselenide "arm" and one of the monoselenide atoms to coordinate to Sn. The compounds were characterized with differential thermal analysis, far-IR, and solid-state UV/vis diffuse reflectance spectroscopy. (C) 1998 Academic Press.