Modeling the coordination between Na, Mg, Ca, Fe, Ni, and Zn with organic acids

Abstract

Hydrogen bonding plays an important role in the coordination of metals with organic acids. Density Functional Theory (DFT) at B3LYP/6-31g(d,p) level is conducted to evaluate total dipole moment, HOMO/LUMO band gap energy and geometrical parameters of COOH. Na, Mg, Ca, Fe, Ni, and Zn were coordinated with COOH of acetic and benzoic acid in the presence of two water molecules. C O is calculated at the same level of theory. Results indicate that the coordination is shifting the characteristic band of COOH and changing the bond distance and bond angles of COOH. The shift was toward lower wavenumbers and it differs from one element to another. It is also indicated that the coordination differs from one element to another, and this could be a reason for this shift. The increase of the total dipole moment is an indicator for the ability of the studied structure for further interaction with its surrounding molecules even after the coordination. The data is confirmed by a decrease in the calculated band gap energy.