Redetermination at 180 K of a layered lanthanide–organic framework

The asymmetric unit of the title compound, poly[(μ(4)-{[bis-(hydrogen phospho-natometh-yl)aza-nium-yl]meth-yl}phospho-nato)lanthanum(III)], [La(C(3)H(9)NO(9)P(3))](n), comprises an La(3+) center and a H(3)nmp(3-) anion (where H(3)nmp(3-) is a residue of partially deprotonated nitrilo-tris-(methyl-ene-phospho-nic acid), namely {[bis-(hydrogen phospho-natometh-yl)aza-nium-yl]meth-yl}-phos-pho-nate). 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 phospho-nate 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.