Solid-state Structural Characterization of a Rigid Framework of Lacunary Heteropolyniobates
In our ongoing investigations of heteropolyniobate chemistry, a phase featuring decorated, A-type trivacant {alpha}-Keggin ions linked by their charge-balancing sodium cations has been isolated and structurally characterized. This is the first heteropolyniobate reported that has a true lacunary structure type. Na{sub 15}[(PO{sub 2}){sub 3}PNb{sub 9}O{sub 34}]{center_dot}22H{sub 2}O (1) [triclinic space group P{bar 1} (No. 2); a = 12.242 (2) Angstroms, b = 12.291 (3) Angstroms, c = 22.056 (4) Angstroms; {alpha}= 93.12 (3), {beta}= 99.78 (3), {gamma}= 119.84 (3); Z = 4, V = 2799.2 (10) Angstroms{sup 3}] is composed of bilayers of the heteropolyanions alternating with layers of hydrated Na{sup +} cations. Sodium cations also bridge the clusters within their layers through Na-Ot-Nb, Na-Ob-Nb2, and Na-Ot-P bonds (t = terminal and b = bridging). This phase is poorly soluble in water, suggesting that it is more characteristic of a framework of linked heteropolyanions rather than a water-soluble heteropolyanion salt. Two-dimensional solid-state {sup 23}Na multiple-quantum magic angle spinning (MAS) NMR of 1 reveals five distinctive chemical and structural environments for sodium, which agrees with the crystallographic data. The {sup 23}Na and {sup 1}H MAS NMR studies further illustrate the rigid and immobile nature of this framework of cations and anions.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 914057
- Report Number(s):
- BNL-78625-2007-JA; INOCAJ; TRN: US0801507
- Journal Information:
- Inorg. Chem., Vol. 45, Issue 3; ISSN 0020-1669
- Country of Publication:
- United States
- Language:
- English
Similar Records
Equilibria between {alpha} and {beta} isomers of Keggin heteropolytungstates
Syntheses, characterization and magnetic properties of two novel inorganic-organic tungstoferrites, [Fe{sup III}{sub 4}(H{sub 2}O){sub 2}(B-{alpha}-Fe{sup III}W{sub 9}O{sub 34}){sub 2}]{sup 10-}