Attachment energy metallocenes

Figure 2. Correlation diagram giving attachment energies of the 3d metallocenes (from ref. 7).

Figure 1. Free energy ladder for electron attachment to metallocenium ions, CP2M, as deduced by charge-transfer equilibria. Reference compounds (Ref. 17) are shown on the left with -aG values. Values of (Equation 8) are shown on the vertical lines for various equilibria, and derived values of -aG for the metallocenes are shown on the right. Values in parentheses are estimates. Temperature 350 K.

Similar experiments, involving electron transfer between an anion and a neutral molecule, yield relative or absolute EAs. The method has been used to determine relative free energies for electron attachment for a variety of metallocenes and /3-diketonate molecules. Electron photodetachment spectroscopy of negatively charged ions is another source for obtaining electron affinities of molecules. These data provide an important component of thermochemical cycles involving oxidation/reduction of metal complexes, and serve as a basis for obtaining other thermochemical values. 

---