A new three-dimensional sodium molybdenum(V) hydroxymonophosphate: Na8(Mo2O4OH)3(PO4)3(PO3OH)·12.25H2O

Abstract

A new sodium molybdenum(v) hydroxymonophosphate, Na₈(Mo₂O₄OH)₃(PO₄)₃(PO₃OH)·12.25 H₂O has been synthesized. It crystallizes in the monoclinic space group P2₁ /c with a=13.024(4), b=25.936(4), c=13.276(3) Å, β=111.72(2)°. Its structure involves Na[Mo₆P₄O₂₇(OH)₄ ]₂clusters similar to those encountered in several other molybdenum(v) hydroxyphosphates. Such clusters built up of two rings of six edge-sharing Mo octahedra interconnected through one NaO₆ octahedron differ from those previously described by the fact that hydrogen is mainly connected to the Mo–O bond forming twelve Mo(O₅OH) octahedra, whereas among the eight tetrahedra one observes two P(O₃OH) tetrahedra and six PO₄ tetrahedra. The originality of this structure deals with the fact that such clusters form with several sodium octahedra, Na(H₂O)₄O₂ and Na(H₂O)₂O₄ , a three-dimensional framework that delimits intersecting tunnels running along a, b and c. The coordination of other sodium cations and H₂O molecules that can be considered as intercalated species is also discussed.