MAGNESIUM AND MANGANESE(II) SALTS OF 2-(PHOSPHONOMETHYL)ACRYLATE

Jaroslaw Mazurek, Tadeusz Lis

Faculty of Chemistry, University of Wroc3aw, F. Joliot-Curie 14, 50-383 Wroc3aw, Poland
e-mail: mazurek@wchuwr.chem.uni.wroc.pl

Keywords: 2-(phosphonomethyl)acrylate, phosphonate analogue of phosphate esters, crystal structure

Interest in phosphonate chemistry and biology is attributed to the fact that the carbon-phosphorus bond in phosphonates, unlike phosphate esters, is not susceptible to hydrolytic actions of phosphatases, imparting stability and longer duration of action under physiological conditions [1]. Phosphonate analogues of biologically important phosphate esters have been found in carbohydrates, amino acids, lipids, nucleotides, etc. [2,3]

2-(Phosphonomethyl)acrylic acid is the analogue of the phosphoenolpyruvic acid, which acts by inhibition of the phosphoenolpuryvate kinase [4]. This work presents two salts of 2-(phosphonomethyl)acrylic acid with the Mg²⁺ and Mn²⁺ cations.

Conformation of all of the anions in both crystals does not differ significantly, with the phosphonate group projected out of the methacrylate backbone. The most difference between anions is the orientation of the phosphonate hydroxyl group in relation to the C2 atom, and the type of interaction with the metal cations.

In the magnesium crystal (I) one of the two independent anions chelates the cation through carboxyl and phosphonate O atoms. The rest of the coordination sphere is from four water molecules forming a distorted octahedron. The second anion does not coordinate the cation. The hydrogen bonds network between anions and the water molecules form the polymeric bilayer parallel to the ab plane. The inner part of the layer is from the cations and water molecules, while the outer one is from the anions.

Approximately octahedral Mn²⁺ cation in II is coordinated by four phosphonate O atoms and two cis water molecules. The Mn²⁺ ions are bridged by two types of centrosymmetric OPO and O bridges. In this way a polymeric chains running along the b axis are formed. The hydrogen bonding network occured in the crystal forms a three dimensional polymeric structure.

I	II

This work was partialy supported by Polish State Comittee for Scientific Research (KBN grant No. 3 T09A 003 012).