K3[Fe3.26V0.74(OH)O(PO4)4(H2O)2]·2H2O: a synthetic leucophosphite

A new iron(III)/vanadium(III) phosphate, K3[Fe3.26V0.74(OH)O(PO4)4(H2O)2]·2H2O (1), has been obtained by hydrothermal synthesis and characterized by single crystal X-ray diffraction, Scanning electron microscopy–energy dispersive X-ray spectroscopy, Inductively coupled plasma atomic emission spectroscopy (ICP), thermogravimetric analysis, and FTIR spectroscopy. Single crystal X-ray diffraction reveals a 3D open framework (monoclinic, space group P21/n, a = 9.6391(7) Å, b = 9.8063(7) Å, c = 9.7268(7) Å, β = 100.71(1)°, and V = 903.38(11) Å3). This structure presents FeIII and VIII in a 4.4 : 1 M ratio with the metal ions in two different crystallographic sites. Both metallic centers have distorted octahedral environments, linked by PO4 tetrahedra, forming channels along the a-axis. The asymmetric unit of K3[Fe3.26V0.74(OH)O(PO4)4(H2O)2]·2H2O presents a {M4(OH)O(PO4)4(H2O)2}3− anionic entity, charge balanced by three K+, which are located within the channels. It is also possible to distinguish M4O2 units whose MIII polyhedra are linked by vertex and edges.