Synthesis and crystal structure of the monoclinic phase of lutetium perrhenate tetrahydrate

Mechanical mixtures of monocrystals of two polymorphous modifications of lutetium perrhenate tetrahydrate Lu(ReO4)3·2H2O: the earlier described triclinic one and a monoclinic modification, isolated for the first time and belonging to a certain new structural type, are obtained by crystallization of Lu(ReO4)3 aqueous solution at 15-20 deg C above H2SO4. For monoclinic Lu(ReO4)3·4H2O crystal structure is studied by the X-ray structural analysis method. The crystal lattice parameters are as follows: a = 7.273(1), b = 14.786(3), c = 13.093(2) A, β = 93.63(1) deg, Z = 4, sp. gr. P21/n. The structure consist of endless chains along [100], formed by interconnected LuO8 polyhedrons and ReO4 tetrahedrons. Chains are linked by hydrogen bond. (author)