Cs3Mo4P4O22: A Mixed Valent Monophosphate Isotypic with K2Mo2P2O11

✍ Scribed by M.M. Borel; A. Leclaire; A. Grandin; B. Raveau

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 200 KB
• Volume: 108
• Category: Article
• ISSN: 0022-4596
• DOI: 10.1006/jssc.1994.1049

✦ Synopsis

A new mixed valent molybdenum phosphate, (\mathrm{Cs}{3} \mathrm{Mo}{4} \mathrm{P}{4} \mathrm{O}{22}) has been isolated. The structure determination of this phase from a single crystal shows its isotypy with the pure (\operatorname{Mo}(\mathrm{V})) phosphate (\mathrm{K}{2} \mathrm{Mo}{2} \mathrm{P}{2} \mathrm{O}{11}). It crystalizes in the space group (P 2_{1} / c) with (a=) 10.134(1) (\AA, b=10.104(1) \AA, c=9.952(1) \AA \AA, \beta=100.44(1)^{\circ}). The (\left[\mathrm{Mo}{2} \mathrm{P}{2} \mathrm{O}{11}\right]{\infty}) framework consists of " (\mathrm{Mo}{2} \mathrm{P}{2} \mathrm{O}{15}) " units built up from two octahedra and two tetrahedra, and delimits large intersecting tunnels where the (\mathrm{Cs}^{+})ions are located. The important difference with (\mathrm{K}{2} \mathrm{Mo}{2} \mathrm{P}{2} \mathrm{O}{11}) deals with the stoichiometry of the interpolated (\mathrm{Cs}^{+})cations and their distribution in the structure: two sorts of sites are occupied by (\mathrm{Cs}^{+})instead of three by (\mathrm{K}^{+}), owing to the larger size of cesium. Another characteristic of this phase concerns the mixed valency of molybdenum (\mathrm{Mo}(\mathrm{V})-\mathrm{Mo}(\mathrm{VI})), compared to the only presence of (\mathrm{Mo}(\mathrm{V})) for (\mathrm{K}{2} \mathrm{Mo}{2} \mathrm{P}{2} \mathrm{O}_{11}). The electronic distribution in the two octahedral Mo sites is discussed. O 1994 Academic Press, Inc.