Intercalation of n-alkylamines into layered materials: a method for the recognition of isomorphism in semicrystalline compounds

n-Alkylamines were intercalated into Ti2O3(H2AsO4)(2). 2H(2)O (TiOAs) and Z r2O3(HAsO4). 3H(2)O (ZrOAs) by exposing the solids to the amine vapour. The formulae of the intercalation compounds are Ti2O3(H2AsO4)(2).1.7C(n)H(2n+1 -)NH(2). 2H(2)O and Zr2O3(HAsO4).0.6C(n)H(2n+1)NH(2). 2H(2)O (n=3-6), respe ctively. The intercalated amines form bimolecular layers in the interlayer space of the polyvalent metal arsenates. The changes in the basal spacing o f the intercalation compounds as a function of the length of the alkyl chai n were used for evaluation of the free area associated with each active cen tre in the arsenate layers: 11.8 (TiOAs) and 10.8 Angstrom (2) (ZrOAs). The comparison of these data with analogous data reported for n-alkylamine int ercalation into other metal(IV) arsenates and metal(IV) phosphates resulted in the formulation of a procedure for the recognition of isomorphism in se micrystalline compounds.