K2FeF5: Synthesis and Crystal Structure of a New Form

Abstract

Single crystals of a new form of K2FeF5 have been grown by hydrothermal synthesis in concentrated HF solutions. The structure is established from single crystal X-ray diffraction data: space group Pbam , Z = 8, a = 7.3591(4) Å, b = 23.0897(10) Å, and c = 5.7054(2) Å (R = 0.0257, Rw = 0.0273 for 1530 independent reflections and 84 parameters). The network is built with infinite and single linked cis -chains of FeF6 octahedra, running along the c axis, separated by 10 coordinated potassium ions. The structure is compared to those of Rb2CrF5 and of the previously known K2FeF5 form (Pbcn), showing respectively the same single linked and double linked chains of MF6 octahedra.