Hydrothermal syntheses and crystal structures of three zinc succinates: Zn(C4H4O4)-, Zn(C4H4O4)- and K2Zn(C4H4O4)2

Three zinc succinate coordination polymers have been synthesised hydrothermally. Two polymorphs of Zn(C4H4O4) adopt three-dimensional structures consisting of tetrahedral Zn atoms isolated from each other via bis-bidentate succinate moieties. The polymorphs differ in the conformation of the succinate group, the form (I) having syn-periplanar geometry whereas the form (II) has anti-periplanar geometry. K2Zn (C4H4O4)2(III) has a layered structure also composed of isolated tetrahedral Zn units. In this case the two crystallographically distinct succinate groups, one of each conformer, have bis-monodentate coordination, acting as both inter- and intra-layer bridges between neighbouring Zncontaining layers. The double zinc succinate layers are separated along the b-axis by inter-layer potassium ions.