CS-6[MO7O24].7H(2)O

In an attempt to crystallize a new diphosphonate complex of polyoxomol ybdate at pH 7, colorless crystals of the caesium salt of heptamolybda te, Cs-6[Mo7O24].7H(2)O, were obtained. The structure of the heptamoly bdate anion was first reported by Lindqvist [Arkiv Kemi (1950), 2, 325 -341] and subsequently confirmed by other groups. The structure report ed here is the first of a caesium salt of heptamolybdate; the coordina tion of the caesium counterions is of interest.