Example Zn2 aq and Metal Binding of Zn Fingers

This difference between Fe2+ and Zn2+ is eventually related to the presence of unfilled d-orbitals in Fe2+, whereas Zn2+ is a closed-shell ion. The organization of these d-orbitals is sensitive to the environment. In bulk water, Fe2+(aq) is coordinated by six water molecules, which leads to the splitting of the d-orbitals into 

In Fig. 9.2 we present results of a first-of-a-kind study of the hydration of the first-transition-row metals within the quasichemical framework. The biphasic behavior of the actual hydration free energy is consistent with features inferred experimentally. Removing the ligand field effects reveals the linear decrease [12]. The results shown in Fig. 9.2 are largely outside the purview of extant simulation techniques, but are treated simply in the quasichemical framework developed below. 

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