Unique charge ordering of manganese in a new mixed valent phosphate image

A new mixed-valent manganese phosphate, View the MathML sourceK3Mn3IIMnIII(PO4)(H0.5PO4)2(HPO4)2, has been synthesized using hydrothermal method. Its monoclinic C 2/c structure (a =12.5506(16) Å, b =10.4816(18) Å, c =13.6723(10) Å, β =103.758(11)°) forms a 3D framework of MnO6 octahedra, MnO5 trigonal bipyramids, PO4 and PO3OH tetrahedra. The main structural feature of this phosphate deals with its [Mn4O16]∞ chains running along View the MathML sourcec⇒, which are interconnected through PO4 and PO3OH tetrahedra, forming intersecting tunnels running along [110], View the MathML source[11¯0] and [001]. The geometry of the [Mn4O16]∞ chains and the charge ordering of manganese in the latter are unique: they consist of trimeric units of divalent manganese “View the MathML sourceMn3IIO12” alternating with single trivalent MnIIIO6 octahedra along View the MathML sourcec⇒. In each “View the MathML sourceMn3IIO12” unit one central MnIIO6 octahedron shares two opposite edges with two MnIIO5 trigonal bipyramids. Along View the MathML sourcec⇒, one Mn(II) octahedron alternates with one Mn(III) octahedron by sharing one corner. The relationships between the structure of this unique charge ordered phosphate and other manganese phosphates are discussed.