Unique charge ordering of manganese in a new mixed valent phosphate K3Mn3IIMnIII(PO4)(H0.5PO4)2(HPO4)2

A new mixed-valent manganese phosphate, K3Mn3IIMnIII(PO4)(H0.5PO4)2(HPO4)2, has been synthesized using hydrothermal method. Its monoclinic C2/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 c⇒, which are interconnected through PO4 and PO3OH tetrahedra, forming intersecting tunnels running along [110], [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 “Mn3IIO12” alternating with single trivalent MnIIIO6 octahedra along c⇒. In each “Mn3IIO12” unit one central MnIIO6 octahedron shares two opposite edges with two MnIIO5 trigonal bipyramids. Along c⇒, 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.

The three-dimensional intersecting tunnels structure of K3Mn3IIMnIII(PO4)(H0.5PO4)2(HPO4)2 presents original [Mn4O16]∞ chains in which “Mn3IIO12” trimeric units alternate with MnIIIO6 octahedra.Figure optionsDownload as PowerPoint slide