Crystal structure and thermal stability of Sm(ReO4)3(H2O)3

Trisaquatris(tetraoxorhenate(VII)) samarium (III), Sm(ReO4)3(H2O)3 was prepared by reaction of Sm2O3 with concentrated HReO4 at room temperature. The pale yellow compound crystallized in the orthorhombic space group Pna21 (No. 33) with four formula units per unit cell (a=1477.6(2) pm, b=846.8(1) pm, c=1150.5(2) pm). The main feature of the crystal structure is the formation of a non-centric three-dimensional network. This arrangement shows distorted tricapped trigonal prism of Sm(H2O)3(ReO4)6/2. The compound releases coordination water in two steps by heating until 450 K and decomposes at ∼1150 K into Sm3ReO8 [Acta Crystallogr. B32 (1976) 3045] by loosing volatile Re2O7. Magnetic properties were investigated for 1.8 K≤T≤320 K