Magnesium, calcium and strontium salts of phenylacetic acid

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 in catena-poly[[[tetraaquamagnesium(II)]-mu-phenylacetato-kappa O-2: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 the a axis. The polymeric chains pack to give alternate inorganic layers and organic bilayers. The Ca and Sr species catena-poly[[[diaqua(phenylacetato-kappa O-2,O')calcium(II)]-mu(3)-phenylacetato-1':1:1 ''kappa O-4:O,O':O'] monohydrate], {[Ca(C8H7O2)(2)(H2O)(2)]center dot H2O}(n), and catena-poly-[[[diaqua(phenylacetato-kappa O-2,O')strontium(II)]-mu(3)-phenylacetato-1':1:1 ''kappa O-4:O,O':O'] monohydrate], {[Sr(C8H7O2)(2)(H2O)(2)]center dot H2O}(n), are essentially isostructural. Both form one-dimensional coordination polymers through a carboxylate group that forms four M-O bonds. The polymeric chains propagate via 2(1) screw axes parallel to the b axis and are further linked in the bc plane by hydrogen bonding involving the non-metal-bound water molecule. Similarly to the Mg salt, both have inorganic layers that alternate with organic bilayers.