Todorov P.Calmes M.Shivachev B.L.Nikolova R.P.2024-07-102024-07-102024-07-102024-07-102011-08-011600-536810.1107/S1600536811029503SCOPUS_ID:80051523662https://rlib.uctm.edu/handle/123456789/226The carb-oxy-lic acid mol-ecule of the title compound, C 11H 20NO 5P·0.25CH 2Cl 2, exists as a zwitterion with the H atom of the phospho-nate group being transferred to the imine N atom. In the asymmetric unit, there are two crystallographically independent acid molecules adopting the same absolute configuration and differing slightly in their geometrical parameters. In each mol-ecule, the imino and carboxyl groups are connected via an intra-molecular N - H⋯O hydrogen bond. Inter-molecular O - H⋯O and N - H⋯O hydrogen bonds induce the formation of layers parallel to the ab plane. The dichloro-methane solvent mol-ecule, with a site occupancy of 0.5, is located between the layers.enArticle