Preparation, magnetic properties and structure of β-Li3CrF6

The β-modification of Li3CrF6 was prepared by heating an appropriate mixture of LiF and CrF3 at 820°C in an argon-filled quartz glass ampoule with subsequent slow cooling to room temperature. β-Li3CrF6 is isotypic to β-Li3VF6 and crystallizes in space group C2/c with a = 14.381(1), b = 8.605(1), c = 10.012(1) Å, β = 94.85(1)°. The structural parameters were refined using single crystal data. A comparison of its structure with that of other β-Li3MF6 (M = Ti, Ga, and Al) compounds is made for the analysis of a static Jahn-Teller effect within quasi-isolated [TiF6]3− octahedra. Emphasis is given to the geometry and coordination number of various LiFn polyhedra. The magnetic moment of the title compound was close to that of a free-ion value. Calculations of the Madelung part of the lattice energy (MAPLE) were performed to ascertain the accuracy of the positional parameters of various atoms in the structure.