Decanuclear compounds

Fig. 3a-c. Differential pulse voltammetric patterns for oxidation of decanuclear compounds in acetonitrile solution a 20 b 19 c 18. Fc indicates the oxidation peak of ferrocene, used as an internal standard... 

Figure 4. Schematic representation of the synthesis of decanuclear compounds. ...

Very interesting oxidation patterns are obtained for decanuclear compounds (Scheme 1 and Table 1). For example, in compound lOC, which contains one Os " and nine Ru " ions, the Os " ion is expected to be oxidized at less positive potentials than the nine Ru ions. Furthermore, because of the different electron donor properties of the ligands, the six peripheral Ru ions are expected to be oxidized at less positive potentials than the three intermediate Ru " ions. In agreement with these expectations, the differential pulse voltammogram of IOC (Figure 12) shows... 

When only polypyridine-type ligands are present, each mononuclear metal-based unit exhibits intense LC bands in the UV region and moderately intense MLCT bands in the visible. As it is shown by the electrochemical behavior vide supra), in the polymetallic species there is some interaction among the neighboring metal-based units. To a first approximation, however, each building block carries its own absorption properties in the polynuclear species so that the molar absorption coefficients exhibited by the compounds of higher nuclearity are huge, as it is clear by a cursory examination of the absorption data reported in Table 3. For example, the spectra of the decanuclear compounds lOB and lOC (Scheme 1 and Table 1)... 

Figure 22. Schematic representation of the energy transfer processes in the decanuclear compounds. For the graphic symbols, see caption to Figure 21.

To illustrate the most interesting electrochemical features of this family of dendrimers, it is reported the results obtained for three strictly related decanuclear compounds and the highest nuclearity compound of this dendrimer family, that is, a docosanuclear complex. 

Figure 20 Schematic view of the structure of a decanuclear compound. Reproduced with...

The final dominant alkyl alkoxides are the Xns tert-butyl)methoxide (TBM) derivatives. These were foimd for the -1-3 to adopt a dimer structure with the boimd solvents. For the Yb + cation, a monomer with the bound solvent was isolated. It is of note that other alkyl alkoxide ligands have been sporadically structurally investigated with the majority of these compounds yielding solvated dinuclear complexes. One interesting species is the methoxyethoxide (OEtOMe) derivative of Dy , which forms an unusual decanuclear starshaped species (see Figure 3). 

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