The reaction ofM(M=Pd, Zn, Cd, Hg) with a molten mixture ofA2Se/P2Se5/Se produced the quaternary compoundsA2MP2Se6(A=K, Rb, Cs;M=Pd, Zn, Cd, Hg). The crystals ofA2MP2Se6are air- and water-stable. For Cs2PdP2Se6(1): monoclinicC2/c (No. 15) witha=12.9750(4) Å,b=8.3282(2) Å,c=13.0568(1) Å,β=102.940(2)°,Z=4, andR/Rw=6.7/7.5%. K2ZnP2Se6(2), K2CdP2Se6(3), Rb2CdP2Se6(4), and Cs2CdP2Se6(5) are isostructural. Rb2CdP2Se6(4): monoclinicP21/n(No. 14) witha=6.640(1) Å,b=12.729(2) Å,c=7.778(1) Å,β=98.24(1)°,Z=2, andR/Rw=3.7/4.9%. K2HgP2Se6(6) and Rb2HgP2Se6(7), are isostructural. K2HgP2Se6(6): monoclinicP21/c(No. 14) witha=13.031(2) Å,b=7.308(2) Å,c=14.167(2) Å,β=110.63(1)°,Z=4, andR/Rw=5.6/7.1%. Compounds 1-7 contain the ethane-like [P2Se6]4-group. Compound 1 has a one-dimensional structure with Pd2+in square-planar coordination. Compounds 2-5 also have one-dimensional structures related to the TiI3structure type. TheM2+ions and the P-P pairs reside in Se octahedra that share opposite faces in the chain direction. Compounds 6 and 7 have a related one-dimensional structure but with Hg2+in tetrahedral coordination. The solid state single-crystal optical absorption and far-IR spectra of the compounds are reported. Compounds 2-7 melt congruently in the 540-773°C region, whereas 1 melts incongruently.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Ceramics and Composites
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry