Synthesis, Crystal Structure, and Properties of Polymeric Rb12Nb6Se35, a Novel Ternary Niobium Selenide Consisting of Infinite Anionic Chains Built Up by Nb2Se11Units Containing an Uncommon Se4−3-Fragment
✍ Scribed by Peter Dürichen; Michael Bolte; Wolfgang Bensch
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 295 KB
- Volume
- 140
- Category
- Article
- ISSN
- 0022-4596
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✦ Synopsis
Rb 12 Nb 6 Se 35 is the first ternary niobium polyselenide composed of infinite anionic chains. These are well separated by rubidium cations. It crystallizes in the orthorhombic space group Pbcn with unit cell dimensions a ؍ 8.5811(1) A s , b ؍ 13.7152(1) A s , c ؍ 56.5225(4) A s , and Z ؍ 4. The least-squares refinement against F 2 with anisotropic displacement parameters for all atoms yields R1 ؍ 5.78 and wR2 ؍ 12.81. The anionic polymeric chains are arranged in layers parallel to the (010) plane, and successive planes are rotated by 35°against each other. Nb 2 Se 11 units composed of two face-sharing NbSe 7 pentagonal bipyramids are the building blocks of the structure. They are interconnected by Se 2 \ 2 and Se 2 \ 3 polyanions, giving rise to infinite 1 [Nb 6 Se 35 ] 12 \ chains. Within the Nb 2 Se 11 units an unusual nearly linear Se 3 fragment is found which must be formulated as Se 4 \ 3 .