Synthesis and Crystal Structure of a New Open‐Framework Iron Phosphate (NH4)4Fe3(OH)2F2 [H3(PO4)4]: Novel Linear Trimer of Corner‐Sharing Fe(III) Octahedra.

The title compound is hydrothermally synthesized from an aqueous mixture of FeCl3, (NH4)H2PO4, and HF with a Fe:NH4:P:F molar ratio of 1.2:1:1:1.8 (autoclave, 110, 120, and 130 °C for 24, 24, and 72 h, resp.).