STRUCTURAL SYSTEMATICS OF RARE-EARTH COMPLEXES .2. STRUCTURAL CHARACTERIZATION OF LANTHANOID(III) PICRATE HYDRATES - THE TRICLINIC P(1)OVER-BAR, 11.5 HYDRATES OF THE LATER RARE-EARTHS AND YTTRIUM

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, P1BAR, a 20.043(7) --> 20.019(5), b 11.533(2) --> 11.471(2), c 8.1567(7) --> 8.1538(8) angstrom, alpha 88.60(1) --> 88 --> 40(1), beta 87.12 (2) --> 87.06(1), gamma 75.07(2) --> 75.05(2)-degrees, V 1819 --> 1807 angstrom3 (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, P2(1)/c, series found for La --> Pr and Nd --> Tb, in which the complex cation contains two picrate anions.