Studies on peroxomolybdates. XIX. Crystal structure of potassium heptaoxotetraperoxotrimolybdate(VI)-water( [formula omitted]) K 4[Mo 3O 7(O 2) 4]·2H 2O

Abstract

The crystal structure of potassium heptaoxotetraperoxotrimolybdate(VI)-water( 1 2 ), K 4[Mo 3O 7(O 2) 4]·2H 2O, has been determined from single-crystal X-ray diffraction data. The yellow compound crystallizes in the triclinic space group P 1 with a = 8.470(1), b = 12.297(3), c = 8.407(2) A ̊ , α = 103.56(2)°, β = 104.32(1)°, γ = 103.40(1)°, V = 784.8(3) A ̊ 3 and Z = 2. Full-matrix least-squares refinement of 218 structural parameters gave R = 0.026 for 4415 observed [ I > 3 σ( I)], independent reflections. In the [Mo 3O 7(O 2) 4] 4− anion two molybdenum atoms are seven-coordinated and one molybdenum atom is four-coordinated. The anion can be described as being composed of two edge-sharing pentagonal bipyramids sharing one common corner with a tetrahedron. In the pentagonal bipyramids the molybdenum atoms are displaced 0.314–0.317 Å from the equatorial plane towards the double-bonded apical oxygen atom. The three molybdenum atoms are situated at the corners of an isosceles triangle with the two seven-coordinated molybdenum atoms (Mo pbp) at the base. Selected bond distances: MoO peroxo 1.933(3)-1.991(3) Å, Mo pbpO apical 1.683(3)–1.695(3) Å, Mo pbpO apical 2.301(2)–2.334(2) Å and (OO) peroxo 1.460(5)–1.487(4) Å. Mo ⋯ Mo is 3.3612(4), 3.7037(5) and 3.7306(7) Å.