Amine-intercalated layered Sn<SUP>II</SUP> phosphates with open-framework structures

Abstract

Three new SnII phosphate materials, [NH3(CH2)3 NH2(CH2)2NH2(CH2)3 NH3]&#183;2[Sn2P2O8] (I), [(N2C5H14)2][Sn4P4 O16]&#183;3H2O (II) and [(N2C5H14)] [Sn2P2O8]&#183;H2O (III), have been synthesised by means of hydrothermal methods using N,N'-bis(3-aminopropyl)ethylenediamine (BAPEN; for I) and homopiperazine (H-PIP; for II and III), respectively, as the structure-directing organic amines. The solids I-III have layered architectures. The structures of all three compounds consist of strictly alternating vertex-sharing trigonal-pyramidal SnO3 and tetrahedral PO4 moieties forming infinite layers possessing apertures bound by 4- and 8-T atoms (T = Sn, P). The distorted 4- and 8-membered apertures within the layers suggest the subtle influence of the lone-pair of electrons of SnII on the structure. The interlamellar space is occupied by the protonated organic amine molecules which interact with the framework through N-H&#183;&#183;&#183;O hydrogen bonding. The compounds I-III bear some structural relationship to the layered zinc phosphite phases