Preparation, infrared spectrum and thermal studies of [Zn2(H2O)4(SO4)2] complex formed by the reaction of urea with zinc (II) sulphate

Abstract The newly-prepared bridged disulphato complex [Zn2(H2O)4(SO4)2] was obtained by the reaction of aqueous solutions of ZnSO4 · 7H2O and urea at ≅ 80°C. The i.r. spectrum of the complex shows the characteristic bands of coordinated sulphate ions as well as coordinated water, and was interpreted on the basis of C2v symmetry. Differential thermal analysis (DTA) and thermogravimetric analysis (TG) of the complex were also carried out. The data obtained indicate that the decomposition of the complex in two stages corresponds to the two different Zn(II)-ligand bond types, one of water and the second of sulphate. Activation energies for these bonds are calculated. A general mechanism describing the formation of the complex is suggested.