Ein Heteropolyanion als Einschlußverbindung / A Heteropolyanion with Clathrate Character

Abstract

Tetrabutylammoniumdodecatungstophosphate, [N(C 4 H 9 ) 4 ] 3 PW 12 O 40 exists in two different forms. The anion of the first one represents the regular “Keggin-Structure” (α-type) with T d -Symmetry. The second isomer, crystallizing in the triclinic space group P1̄ with lattice parameters a = 13.897 Å, b = 15.410 Å, c = 19.535 Å, α = 95.11°, β = 92.88°, γ = 90.46° contains a neutral W 12 O 36 moiety with centrosymmetric tungsten and oxygen positions built from tetragonal-pyramidal WO 5 units. In the central cavity a disordered PO 4 3- anion is enclosed. For the new isomer the term γ-type is proposed.