Structure of a novel polynuclear europium compound with N-phosphonomethylglycine: heptaaquaperchloratodi-mu(4)-N-phosphonomethylglycine-dieuropium(III) triperchlorate monohydrate, [Eu-2(HO3PCH2NH2CH2CO2)(2)(H2O)(7)(ClO4)]center dot 3ClO(4)center dot H2O

The solid-state structure of the europium(III) complex with N-phosphonometh ylglycine (PMG) has been obtained from aqueous solution, at pH ca. 1.6, whe re a 1 : 1 M : L molar ratio has been kept. The crystal structure of the [E u-2(HO3PCH2NH2CH2CO2)(2)(H2O)(7)(ClO4)] . 3ClO(4) . H2O compound has been d etermined by single-crystal X-ray diffraction. In the structure of the titl e compound a two-dimensional polymer is formed, with an unexpected architec ture. The oxygen atom of one of four perchlorate groups is engaged in the c oordination besides that of the PMG groups. The glyphosate molecules are pr esent as zwitterions. The polymeric chains are composed of two types of dim eric subunits. The first one is created by simple and chelating carboxyl br idges, and the second by phosphonate groups; in the latter type the dimeric unit coordination of metal ions is completed by two oxygen atoms of two pe rchlorate groups. In the first subunit four, and in the second subunit thre e water molecules are coordinated by each europium atom. The eighth water m olecule and three of four perchlorate groups are outside the metal coordina tion. Therefore, two non-equivalent metal sites, eight- and nine-fold coord inated, exist in the structure. The structure is stabilized by an extended network of hydrogen bonds. The conformations of the two PMG molecules are q uite different.