Redetermination at 180 K of a layered lanthanide–organic framework

The asymmetric unit of the title compound, poly[(μ₄-{[bis­(hydrogen phospho­natometh­yl)aza­nium­yl]meth­yl}phospho­nato)lanthanum(III)], [La(C₃H₉NO₉P₃)]_n, comprises an La³⁺ center and a H₃nmp³⁻ anion (where H₃nmp³⁻ is a residue of partially deprotonated nitrilo­tris­(methyl­ene­phospho­nic acid), namely {[bis­(hydrogen phospho­natometh­yl)aza­nium­yl]meth­yl}­phos­pho­nate). This study concerns a structural redetermination using single-crystal X-ray diffraction data, collected at the low temperature of 180 K, of a recently investigated material whose structural details have been proposed from powder X-ray diffraction studies [Silva et al. (2011). J. Am. Chem. Soc. 133, 15120–15138]. The main difference between the two models rests on the position of the H atoms. While two H atoms were modeled as attached to the same phospho­nate group in the powder determination, in the current model, the same H atoms are instead distributed among two of these groups. The sample studied was an inversion twin.

[(E)-1-(Naph­thalen-2-yl)ethyl­idene](naph­thalen-1-ylmethyl)amine

The title compound, C₂₃H₁₉N, was obtained unexpectedly from the reaction of [Eu(nta)₃(PzPy)] {Hnta = 1-(2-naphtho­yl)-3,3,3-trifluoro­acetone and PzPy = 2-[3(5)-pyrazol­yl]pyridine} with 1-naphthyl­methyl­amine. The 1- and 2-naphthyl groups are essentially planar [r.m.s. deviations of 0.007 and 0.011 Å, respectively] and subtend angles of 38.69 (11) and 16.50 (11)°, respectively, with the central CH₃—C=N—CH₂ unit, which is also almost planar [r.m.s. deviation = 0.002 Å]. In the crystal, the mol­ecules are disposed in zigzag-type fashion, forming layers perpendicular to [100]. Weak supra­molecular C—H...π inter­actions contribute to the packing forces.

1,3-Dicyclo­hexyl­imidazolidine-2,4,5-trione: a second polymorph

The title compound, C₁₅H₂₂N₂O₃, was obtained as a by-product of oxidative cleavage of 1,3-dicyclo­hexyl-(3-oxo-2,3-dihydro­benzofuran-2-yl)imidazolidine-2,4-dione. Herein, we report the crystal structure of a second polymorph, which was obtained by crystallization from an ethanol solution at 253 K, instead of slow evaporation of the same solvent at room temperature. While the first polymorph [Talhi et al. (2011). Acta Cryst. E67, o3243] crystallized in the non-centrosymmetric space group P2₁2₁2₁, this second polymorph crystallizes in the centrosymmetric space group P2₁/n. Compared to the first polymorph, in the crystal no C=O...C=O inter­actions were found (C...O inter­molecular distance longer than 3.15 Å) and instead, close packing of individual mol­ecular units is mediated by C—H...π and weak C—H...O inter­actions.