Magnesium, calcium and strontium salts of phenylacetic acid

Abstract

Three alkaline earth metal salts of phenylacetic acid were examined and all were found to have similar structural types to analogous salts of benzoic and halobenzoic acids. Thus, a synchrotron study shows that the cations incatena-poly[[[tetraaquamagnesium(II)]-μ-phenylacetato-κ2O:O′] phenylacetate], {[Mg(C8H7O2)(H2O)4](C8H7O2)}n, form a one-dimensional coordination polymer that propagates through Mg—O—C—O—Mg interactions involving both crystallographically independent Mg centres (Z′ = 2) and through translation along theaaxis. The polymeric chains pack to give alternate inorganic layers and organic bilayers. The Ca and Sr speciescatena-poly[[[diaqua(phenylacetato-κ2O,O′)calcium(II)]-μ3-phenylacetato-1′:1:1′′κ4O:O,O′:O′] monohydrate], {[Ca(C8H7O2)2(H2O)2]·H2O}n, andcatena-poly[[[diaqua(phenylacetato-κ2O,O′)strontium(II)]-μ3-phenylacetato-1′:1:1′′κ4O:O,O′:O′] monohydrate], {[Sr(C8H7O2)2(H2O)2]·H2O}n, are essentially isostructural. Both form one-dimensional coordination polymers through a carboxylate group that forms fourM—O bonds. The polymeric chains propagatevia21screw axes parallel to thebaxis and are further linked in thebcplane by hydrogen bonding involving the non-metal-bound water molecule. Similarly to the Mg salt, both have inorganic layers that alternate with organic bilayers.