A new simple route for synthesis of cadmium(II), zinc(II), cobalt(II), and manganese(II) carbonates using urea as a cheap precursor and theoretical investigation

Abstract

ABSTRACT. The MnCO₃.H₂O, CoCO₃.4H₂O, ZnCO_3, and CdCO₃, respectively, were synthesized through a new precise, easy pathway for the reaction of MnI₂, CoI₂, ZnI_2, or CdI₂ aqueous solutions with a cheap precursor-urea for 10 h at ~ 70 ^oC. The IR spectra of reaction products designate the presence of characteristic bands of ionic carbonate, CO₃^2– and absence of the individual bands of urea. The (CO₃)^2- ion is planar and therefore, it belongs to the D_3h symmetry. It is expected to display four modes of vibrations. The stretching vibrations of the type; n(C-O) is observed in the range of (1376-1503) cm^-1 while another stretching vibration n(C-O) is observed in the region 1060-1079 cm^-1. The out of plane of vibration d(OCO) is observed in the range of (833-866) cm^-1 while, the angle deformation bending vibration d(OCO) appear in the range of (708-732) cm^-1. The infrared spectra of metal carbonate, show that, this product clearly has an uncoordinated water. The band related to the stretching vibration n(O-H) of uncoordinated H₂O is observed as expected in the range of ~ 3000 cm^-1. A general mechanism explaining the synthesis of carbonate compounds of cadmium(II), zinc(II), cobalt(II), and manganese(II), are described. Moreover, the DFT outcomes using B3LYP/LanL2DZ (basis set) agree with the experimental results.

KEY WORDS: Carbonate, CoI₂, Infrared spectra, Urea, DFT

Bull. Chem. Soc. Ethiop. 2022, 36(2), 363-372.                                                               

DOI: https://dx.doi.org/10.4314/bcse.v36i2.10