The Structure of a meso-Type Heteropolyion of Tetrahydrogen Disodium Dodecamolybdohexaphosphonate(III) (6-) Contained in [NEt4]6 [H4Na2(PH)6Mo12O54] ×4H2O.

The structure of [NEt4]6[H4Na2(PH)6Mo12O54]·4H2O (1) has been determined by the single-crystal X-ray method. The crystals are monoclinic, space group of C2/c, with cell parameters a = 23.790(3), b = 16.319(2), c = 28.788(3) A, β = 114.365(7)°, and Z = 4. The structure model was refined by full-matrix least squares to R = 0.0624 and Rw = 0.0661 for 6798 independent reflections with Fo > 3σ(F) and in 2θ < 50°. The existence of a meso-type heteropolyion [H4Na2(PH)6Mo12O54]6− (2) in the title crystals has been confirmed. It is composed of a pair of enantiomeric moieties of [H2Na(PH)3Mo6O27]3− (3 and 3i, respectively) which are linked by sharing Na+ ions; here, the superscript i denotes the symmetrical operation code of (1/2−x, 1/2−y, −z). The six MoO6-octahedra contained in the respective moieties are arranged to form Plus- and Minus-helices.