Synthesis and structure of cadmium and zinc complexes of dehydroacetic acid

The cadmium and zinc complexes of Dehydroacetic Acid (DHA) Zn(DHA)2(H2O)2 and Cd(DHA)2(H2O)2 were synthesized and the derivatives Zn(ADH)2(DMSO)2 and Cd(ADH)2(DMSO)2 were prepared through substitution of the water ligands by DMSO. To characterize structural differences between the Cd and Zn complexes, a series of analyses were carried out: 1H, 13C, and 113Cd NMR in solution and 13C and 113Cd NMR in the solid state, infra-red spectra, thermo gravimetric analysis (TGA), differential calorimetric analysis (DSC) and elemental analysis (CHNO). The X-ray crystal structures of the complexes Zn(DHA)2(DMSO)2 and Cd(DHA)2(DMSO)2 are also reported. The coordination around the metal atoms in the solid state is best described as distorted octahedra. The two chelating DHA ligands define an equatorial plane and the axial positions are occupied by two monodentate DMSO ligands coordinated by oxygen atoms, in the trans,trans,trans configuration. Significant differences were found between the Cd and Zn coordination spheres, with the latter forming relatively looser octahedral complexes.