Studies on peroxomolybdates XVIII. Crystal structure of ammonium μ-fluoro-μ-oxo-bis[oxodiperoxomolybdate(VI)]-water(2/1), (NH4)3[FO{MoO(O2)2}2]·12H2O, a dibridged peroxodimolybdate

Abstract The crystal structure of ammonium μ- fluoro -μ- oxo-bis[oxodiperoxomolybdate(VI)]-water (2 1) , (NH 4 ) 3 [FO{MoO(O 2 ) 2 } 2 ]· 1 4 H 2 O , has been determined from single-crystal X-ray diffraction data. The yellow compound crystallizes as multiple-twins in the monoclinic space group P 2 1 / c with a = 13.803(3) A , b = 11.230(2) A , c = 15.975(3) A , β = 109.46(2)° and Z = 8. Full-matrix least-squares refinement of 316 structural parameters gave R = 0.057 for 3265 observed [ I > 3 σ ( I )], independent reflections. The [FO{MoO(O 2 ) 2 } 2 ] 3− anions, of which there are two crystallographically different ones in the asymmetric unit, have approximately C 2v symmetry and are composed of two edge-sharing pentagonal bipyramids, the molybdenum atoms thus being seven-coordinated. The molybdenum atoms are displaced 0.312–0.365 A from the equatorial planes towards the respective double-bonded apical oxygen atom. Bond distances are as follows: MoO peroxo 1.884(10)–1.975(8) A, Mo = O apical 1.670(8)–1.682(8) A, MoF bridge 2.246(6)–2.313(6) A, MoO bridge 1.925(7)–1.941(7) A and (OO) peroxo 1.436(15)–1.465(12) A. Mo ··· Mo is 3.369(1)–3.379(1) A, MoOMo 120.5(4)–122.6(4)° and MoFMo 94.0(2)–95.5(2)°. The powder photograph of the title compound was recorded at room temperature and was indexed.