Structural Systematics of Rare Earth Complexes. II. Structural Characterization of Lanthanoid(III) Picrate Hydrates: the Triclinic P1, 11.5 Hydrates of the Later Rare Earths and Yttrium

Abstract

Picrates of dysprosium(III), holmium(III), erbium(III), thulium(III), ytterbium(III), lutetium(III) and yttrium(III) have been found to crystallize as needles from aqueous solution, seemingly best described as 11.5 hydrates. Single-crystal X-ray structure determinations have been performed at c. 295 K on the Dy , Er , Lu and Y species, and show them to be isomorphous , triclinic, Pī , a 20.043(7) → 20.019(5), b 11.533(2) → 11.471(2), c 8.1567(7) → 8.1538(8) Ǻ, α 88.60(1) → 88.40(1), β 87.12(2) → 87.06(1), γ 75.07(2) → 75.05(2)°, V 1819 → 1807 Ǻ³ ( Dy → Lu; the Y and Er values are intermediate). Complex ions [ Ln ( pic )(OH₂)₇]²⁺ are observed, with a pair of uncoordinated picrate anions and 4.5 lattice water molecules; this result is in contrast to that of the monoclinic, P 2₁/c, series found for La → Pr and Nd → Tb, in which the complex cation contains two picrate anions.