Hyperbranched polymers, organometallic complexes

Another application of hyperbranched polymers as supports for catalysts is their use as backbones for the covalent attachment of organometallic fragments. NCN-pincer complexes (NCN-pincer = 2,6-bis[(dimethylamino)-methyl] phenyl anion) are attractive building blocks for catalytic reactions [20,21], Covalent introduction of the transition-metal complexes can also be of interest for visualization and imaging of dendritic polymers by transmission electron microscopy (TEM). 

In order to directly synthesize organometallic hyperbranched polymers, all the above described established methods could be utilized to knit metal-containing monomers together, provided they are stable under the applied polymerization conditions and do not interfere with the reaction mechanism. As an alternative, suitable pure organic hyperbranched polymers can be functionalized with organometallic complexes. Both approaches have been utilized by other research groups and will be briefly reviewed at the beginning of Chapters 3 and 4. 

Recently, Abd-El-Aziz and colleagues reported different hyperbranched poly(arylethers) (4,5) and poly(arylthioethers) (6) containing cyclopentadienyliron moieties, which were successfully furnished by nucleophilic substitution of A + Bj type monomers (Scheme 2.3) [54], The polymers were thoroughly characterized by standard spectroscopic analysis techniques, they exhibited generally low viscosities, and the organometallic complexes were stable up to 230 °C, as evaluated by thermal gravimetric analysis (TGA). 

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