STRUCTURE OF AN HYDRATED TETRAPROPYLAMNONIUM POLYTUNGSTATE H3W12O40[N(C3H7)(4)](5)CENTER-DOT-2H(2)O

An hydrated polytungstate H3W12O40[N(C3H7)(4)](5) .2H2O has been prepared. Its crystal structure was determined from single crystal XRD data and refined to a conventional R = 0.039 (R(W) = 0.039) for 2907 unique reflections with I > 3 sigma(I). It crystallizes in the quadratic system with the unit cell parameters: a = 20.24(1) Angstrom, c = 46.88(3) Angstrom, Z = 8, space group I4(1)/a (n degrees 88). Its structure can be described from [W12O40] Keggin clusters, and tetrapropylammonium ions. Groups of four water molecules form hydrogen bonds between each other and with the terminal oxygens of the [W12O40] groups, in order to ensure the cohesion of the structure. The Keggin clusters in this structure are in a symmetric configuration, on a two-fold axis, contrary to those described in the litterature.