Structure and complexation mechanism of aqueous Zn(II)-acetate complex studied by XAFS and Raman spectroscopies.

In this work, the structure of Zn acetate has been determined by a combination of X-ray absorption fine structure and Raman spectroscopy. We have analyzed the local atomic environment and the main vibrational bands of the acetate and Zn acetate at different pH. The results suggest that Zn acetate complex acquires a bidentate structure that modifies its first coordination shell. Meanwhile, the coordination shell of the hydrated Zn cation is formed by 6 hydroxides at a mean distance of 2.06 Å, the coordination shell of the Zn cation in the complex is formed by 2 hydroxides and 2 oxygens from the carboxyl group of the acetate, at a mean Zn-O distance of 1.96 Å. The structure of the Zn acetate complex is compared to those of Zn malonate and Zn citrate, none of which present a reduction in the coordination shell neither a shrinkage of the Zn-O shell distance.