A MOLYBDENOTUNGSTEN MONOPHOSPHATE WITH AN OPENED STRUCTURE K6.6MO2.36W3.64O15(PO4)(4)

A new ''MoW'' monophosphate K6.6Mo2.36W3.64O15(PO4)(4) has been synthe sized. This complex opened structure crystallizes in the <R(3)over bar > group with a=17.545(2) Angstrom and c=15.714(2) Angstrom. The [M(6)P (4)O(31)](infinity) framework can be described from M(3)P(3)O(19) and M(6)P(6)O(48) units. The first unit consists of one PO4 tetrahedron sh aring its apices with three MO(6) octahedra, whereas the second one fo rms hexagonal rings in which one MO(6) octahedron alternates with one PO4 tetrahedron. Another interesting feature of this framework deals w ith the existence of spiral-like octahedral [MO(5)](infinity) chains r unning along --> c, so that the structure can also be described as an assemblage of these chains through PO4 tetrahedra. This framework offe rs large cages that communicate with each other, so that five differen t sites are available for potassium.