Effect of inclining strain on the crystal lattice along an extended series of lanthanide hydroxysulfates Ln(OH)SO4 (Ln = Pr-Yb, except Pm).

A series of trivalent lanthanide hydroxysulfates, Ln(OH)SO(4), (Ln = Pr through Yb, except radioactive Pm) has been synthesized via hydrothermal methods from Ln(2)(SO(4))(3)·8H(2)O by reaction with aqueous NaOH at 170 °C in Teflon lined Parr steel autoclaves, and were characterized by single crystal X-ray diffraction and FT-IR spectroscopy. Two types of arrangements were found in the solid state. The lighter (Ln = Pr-Nd, Sm-Gd) and heavier lanthanide(III) hydroxysulfates (Tb-Yb) are each isostructural. Both structure types exhibit the monoclinic space group P2(1)/n, but the unit cell content is doubled with two crystallographically distinct LnO(8) polyhedra for the heavier lanthanide compounds. The lighter complexes maintain the coordination number 9, forming a three-dimensional extended lattice. The heavier counterparts exhibit the coordination number 8, and arrange as infinite columns of two crystallographically different LnO(8) polyhedra, while extending along the "c" axis. These columns of LnO(8) polyhedra are surrounded and separated by six columns of sulfate ions, also elongating in the "c" direction. The rigid sulfate entities seem to obstruct the closing in of the lighter LnO(9) polyhedra, and show an inclining degree of torsion into the "ac" layers. The crystal lattice of the lighter 4f complexes can sufficiently withstand the tension buildup, caused by the decreasing Ln(3+) radius, up to Gd(OH)SO(4). The energy profile of this structural arrangement then seems to exceed levels at which this structure type is favorable. The lattice arrangement of the heavier Ln-analogues seems to offer a lower energy profile. This appears to be the preferred arrangement for the heavier lanthanide hydroxysulfates, whose crystal lattice exhibits more flexibility, as the coordination sphere of these analogues is less crowded. The IR absorbance frequencies of the hydroxide ligands correlate as a function of the Ln(3+) ionic radius. This corresponds well with the X-ray single crystal analysis data.

Poly[[tetraaquadi-µ(4)-glutarato-µ(2)-terephthalato-dineodymium(III)] heptadecahydrate].

The title compound, [Nd(2)(C(5)H(6)O(4))(2)(C(8)H(4)O(4))(H(2)O)(4)]·17H(2)O, obtained via hydrothermal reaction of Nd(2)O(3) with glutaric acid and terephthalic acid, assembles as a three-dimensional open framework with ten-coordinate Nd-O polyhedra. The asymmetric part of the unit cell contains half a glutarate anion, a quarter of a terephthalate dianion, half an Nd(III) cation, one coordinated water molecule and 4.25 solvent water molecules. Each [NdO(10)] coordination polyhedron is comprised of six O atoms originating from four glutarate anions, two others from a terephthalate carboxylate group, which coordinates in a bidentate fashion, and two from water molecules. The Nd-O distances range from 2.4184 (18) to 2.7463 (18) Å. The coordination polyhedra are interconnected by the glutarate anions, extending as a two-dimensional layer throughout the bc plane. Individual two-dimensional layers are interlinked via terephthalate anions along the a axis. This arrangement results in rectangular-shaped cavities with interstices of approximately 3.5 × 6 × 6.5 Š(approximately 140 Å(3)), which are occupied by water molecules. The Nd(III) cations, terephthalate anions, glutarate anions and one of the interstitial water molecules are located on special crystallographic positions. The Nd-terephthalate-Nd units are located across twofold rotation axes parallel to [100], with the Nd(III) cations located directly on these axes. In addition, the terephthalate anion is bisected by a crystallographic mirror plane perpendicular to that axis, thus creating an inversion centre in the middle of the aromatic ring. The glutarate ligand is bisected by a crystallographic mirror plane perpendicular to (001). One of the solvent water molecules lies on a site of 2/m symmetry, and the symmetry-imposed disorder of its H atoms extends to the H atoms of the other four solvent water molecules, which are disordered over two equally occupied and mutually exclusive sets of positions.

(Acetato-κ2O,O')dihydroxidoytterbium(III) hemihydrate.

The title compound, [Yb(C(2)H(3)O(2))(OH)(2)]·0.5H(2)O, was obtained via hydrothermal reaction of Yb(CH(3)COO)(3)·H(2)O with NaOH at 443 K. The compound forms two-dimensional layers with six crystallographically independent Yb(III) atoms. Four of these form YbO(8) coordination polyhedra, while the coordination number of the remaining two Yb(III) atoms is 7. Five of these coordination polyhedra are interconnected mainly via hydroxide groups, as they build a narrow inner layer that extends infinitely within the ab plane. The sixth Yb(III) atom resides outside this inner layer and builds a terminal YbO(8) coordination polyhedron on the layer surface. Its coordination environment comprises four carboxylate O atoms belonging to three different acetate entities, three hydroxide groups and one water molecule. Adjacent layers experience weak interactions via hydrogen bonds. The Yb-O distances lie in the range 2.232 (4)-2.613 (5) Å.