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Title: {beta}-K{sub 4}La{sub 6}I{sub 14}Os: A new structure type for rare-earth-metal cluster compounds that contains discrete tetrahedral K{sub 4}I{sup 3+} units

Suitable reactions of KI, La, LaI{sub 3}, and Os in niobium tubes at 800--850 C result in black, air- and moisture-sensitive crystals of the quaternary title phase. Isostructural K{sub 4}Pr{sub 6}I{sub 14}Z also exist for Z = Fe, Ru. The title phase was characterized by single-crystal X-ray diffraction (tetragonal, P4/ncc (No. 130), Z = 4; a = 13.117(3), c = 25.17(1) {angstrom} at 23 C). The important structural feature is the constitution (K{sub 4}I){sup 3+}(La{sub 6}I{sub 13}Os{sup 3{minus}}) with a new type of 3D anion network of [(La{sub 6}Os)I{sub 8}{sup i}I{sub 4/2}{sup i{minus}a}I{sub 4/2}{sup a{minus}i}I{sub 2/2}{sup a{minus}a}] clusters that are connected into puckered layers through I{sup i{minus}a} and I{sup a{minus}i} atom pairs that bridge diagonally in the a-b plane. These cluster layers are further interlinked along {rvec c} at trans-vertexes through simple bridging I{sup a{minus}a}. The 14th iodine atom occurs in the unique K{sub 4}I{sup 3+} ions which lie in columns that interpenetrate the La{sub 6}OsI{sub 13} network along c. The present 16-e{sup {minus}} clusters, in contrast with the optimal 18-e{sup {minus}} octahedral cluster configuration, exhibit an uncommon tetragonal elongation and evidently become closed shell, with only a small temperature-independent (van Vleck-like) paramagnetism, {approximately}4 x 10{sup {minus}4} emu mol{sup {minus}1}.
Authors:
;
Publication Date:
OSTI Identifier:
20003192
Resource Type:
Journal Article
Resource Relation:
Journal Name: Inorganic Chemistry; Journal Volume: 38; Journal Issue: 17; Other Information: PBD: 23 Aug 1999
Research Org:
Iowa State Univ., Ames, IA (US)
Sponsoring Org:
National Science Foundation; US Department of Energy
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CRYSTAL STRUCTURE; POTASSIUM IODIDES; LANTHANUM COMPOUNDS; OSMIUM COMPOUNDS; SYNTHESIS; PARAMAGNETISM; PRASEODYMIUM COMPOUNDS