Reversible cation/anion extraction from K2La2Ti3O10: formation of new layered titanates, KLa2Ti3O9.5 and La2Ti3O9

Serpil Gonen, Z. ; Paluchowski, Daniel ; Zavalij, Peter ; Eichhorn, Bryan W. ; Gopalakrishnan, J. (2006) Reversible cation/anion extraction from K2La2Ti3O10: formation of new layered titanates, KLa2Ti3O9.5 and La2Ti3O9 Inorganic Chemistry, 45 (2). pp. 8736-8742. ISSN 0020-1669

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Official URL: http://pubs.acs.org/doi/abs/10.1021/ic060434g

Related URL: http://dx.doi.org/10.1021/ic060434g

Abstract

A new soft-chemical transformation of layered perovskite oxides is described wherein K2O is sequentially extracted from the Ruddlesden-Popper (R-P) phase, K2La2Ti3O10 (I), yielding novel anion-deficient KLa2Ti3O9.5 (II) and La2Ti3O9 (III). The transformation occurs in topochemical reactions of the R-P phase I with PPh4Br and PBu4Br (Ph = phenyl; Bu = n-butyl). The mechanism involves the elimination of KBr accompanied by decomposition of PR4+ (R = phenyl or n-butyl) that extracts oxygen from the titanate. Analysis of the organic products of decomposition reveals formation of Ph3PO, Ph3P, and Ph-Ph for R = phenyl, and Bu3PO, Bu3P along with butane, butene, and octane for R = butyl. The inorganic oxides II and III crystallize in tetragonal structures (II: P4/mmm, a = 3.8335(1) Å, c = 14.334(1) Å; III: I4/mmm, a = 3.8565(2) Å, c = 24.645(2) Å) that are related to the parent R-P phase. II is isotypic with the Dion-Jacobson phase, RbSr2Nb3O10, while III is a unique layered oxide consisting of charge-neutral La2Ti3O9 anion-deficient perovskite sheets stacked one over the other without interlayer cations. Interestingly, both II and III convert back to the parent R-P phase in a reaction with KNO3. While transformations of the R-P phases to other related layered/three-dimensional perovskite oxides in ion-exchange/metathesis/dehydration/reduction reactions are known, the simultaneous and reversible extraction of both cations and anions in the conversions K2La2Ti3O10 ⇔KLa2Ti3O9.5⇔ La2Ti3O9 is reported here for the first time.

Item Type:Article
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Deposited On:10 Nov 2010 06:19
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