Synthesis and crystal structure of acid polyphosphates LnH(PO3)4 (Ln = Sm, Eu)

The compounds SmH(PO 3 ) 4 (I) and EuH(PO 3 ) 4 (II) are synthesized by the thin-layer method; their crystal structures are studied by X-ray crystallography. Compounds I and II are isostructural to each other and to the earlier studied BiH(PO 3 ) 4 . The crystals of I and II are triclinic, space group P1, Z = 2, a = 7.127(2) and 7.108(3) A, b = 8.596(3) and 8.855(3) A, c = 8.890(3) and 8.852(3) A; α = 98.83(3)° and 98.93(2)°, β = 112.46(3)° and 112.46(3)°, y = 107.36(3)° and 107.26(3)°, V = 457.6(3) and 452.5(3) A 3 , ρ c a l c = 3.391 and 3.441 g/cm 3 , respectively.