Structure of tetrakis-pivaloyltrifluoroacetonates of heavy rare earth elements and sodium.: Crystal structure of NaEr(C8H10O2F3)4

The structure of a compound from an isostructural series of pivaloyltrifluoroacetonates of heavy rare-earth elements (REE) (Cd-Lu) and sodium, NaEr(C8H10O2F3)(4), was studied by X-ray diffractometry ("Syntex P2(1)," lambda MoKalpha, 1891 reflections R = 0.0601); a = 13.114(4), c = 21.004(9) Angstrom, V = 3128(2) Angstrom(3), Z = 3, space group P3(1). The structures of this series are of ionic type and contain the [Ln(pta)(4)](-) complex anion and the Na+ cation. The coordination polyhedron of Ln is a tetragonal antiprism, an ssss stereoisomer. Na is surrounded by 4O + 4F in the form of an octahedron with two centered faces. Both polyhedra are distorted (average Er-O distances are 2.325 Angstrom Na-O 2.397 Angstrom Na-F 2.682 Angstrom) and linked by common faces into polymeric helicoidal ribbons extended along the c axis and arranged according to the closest packing law. It is established that the Na cation affects the stereochemistry of the anion. A relationship between the structure of the compound and ifs volatility and crystal morphology is discussed.