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The Mixed Valence Tungsten(IV,V) Compound Na[W 2 O 2 Br 6 ]
Author(s) -
Zheng YueQing,
Peters Karl,
von Schnering Hans Georg
Publication year - 1998
Publication title -
zeitschrift für anorganische und allgemeine chemie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.354
H-Index - 66
eISSN - 1521-3749
pISSN - 0044-2313
DOI - 10.1002/(sici)1521-3749(199809)624:9<1415::aid-zaac1415>3.0.co;2-5
Subject(s) - chemistry , crystallography , octahedron , valence (chemistry) , van der waals force , bromide , intercalation (chemistry) , crystal structure , stereochemistry , inorganic chemistry , molecule , organic chemistry
The reaction of W 6 Br 12 , NaBr, and WO 2 Br 2 in the presence of Br 2 in a sealed silica tube yields Na[W 2 O 2 Br 6 ] together with WOBr 4 and WO 2 Br 2 in the low temperature zone (temperature gradient 1030/870 K). Na[W 2 O 2 Br 6 ] crystallizes orthorhombically in the space group Immm (no. 71) with a = 3.775 Å, b = 10.400 Å, c = 13.005 Å and Z = 2. Pairs of condensed trans ‐[WO 2 Br 4 ] octahedra with a common Br 2 edge form along [100] double chains ∞ 1 [W 2 O 4/2 Br 6 ] 1– via the oxygen atoms. The mixed valent tungsten atoms are bonded to W 2 pairs with a 2 c–3 e bond (d(W–W) = 2.946 Å, d(W–O) = 1.888 Å, d(W–Br b ) = 2.537 Å, d(W–Br t ) = 2.535 Å, ∢O–W–O = 177.4°, ∢Br b –W–Br b (endocyclic) = 109.0°). The Na + cations connect the anionic double chains to form two‐dimensional layers parallel (001), which interact by van der Waals forces. The cations are eightfold coordinated by a cube of the terminal Br t ligands of the polymeric anions (d(Na–Br) = 3.138 Å). Na[W 2 O 2 Br 6 ] may be discussed as an intercalation compound of the oxide bromide WOBr 3 .