DIPOTASSIUM HEXAHYDROGEN-ALPHA-HEXAMOLYBDOPLATINATE(IV) PENTAHYDRATE, K-2[H-6-ALPHA-PTMO6O24].5H2O

The structure of the fully protonated hexamolybdoplatinate polyanion salt K-2[H-6 alpha-PtMo6O24].5H(2)O has been determined from X-ray diffraction data. This polyanion has a center of symmetry and protonation of the O atoms is different from that of heteropolyanions having the so-called Anderson structure, [X(n+)(OH)(6)Mo6O18]((6-n)-) (X is a hetero atom), where all the O atoms in the central XO(6) octahedron are protonated. In the present compound, four central (Pt-Oc-Mo2) and two bridging (Mo-Ob-Mo) O atoms are protonated.