Organometallic polymers arene complexes

Apart from the metal atom aggregation reactions described below, bis(arene)metal complexes of the early transition metals are resistant to ligand displacement The rings on the corresponding bis(naphthalene)metal species (41) are by, contrast, labile. Polymer-supported analogs of these naphthalene compounds with vanadium and chromium are known (42), but Ti atoms attack the polymer at the silicon ether linkage. These and other hybrid polymers can be further modified once the metal atom is incorporated. Thus a-methyl naphthalene is displaced from the hybrid organometallic polymer shown in Scheme 7 (43). 

A number of research groups have reported the preparation of a large number of star-shaped molecules and dendrimers containing ferrocenyl or arene cyclopentadienyliron complexes at the core or the peripheries.300-320 A number of these dendrimers were prepared via cyclopentadienyliron-mediated per-alkylation, -benzylation and -allylation reactions of cationic tri-, tetra- and hexamethylbenzene complexes. These dendrimers were multifunctional materials and have been used in the synthesis of branched organic and organometallic polymers. 

In the first part of this article, focusing attention on polymer-supported cobalt phosphine complex 1 and arene ruthenium complex 2, we review contributions from our laboratory that show how organometallics can be efficiently attached to derivitised polystyrene and we outline their synthetic versatility.2,3 Following this, we discuss the preparation of a supported ruthenium complex, 3, and its use in oxidation and transfer hydrogenation catalysis. 

The ability of n-arene metal complexes to coordinate additional metal atoms may be significant in the early stages of metallization of some phenyl-rich polymers. At the lowest coverages of say chromium on polystyrene, (arene)2Cr may be formed. With continued accumulation of metal these compounds may rapidly convert to thermally unstable organometallic cluster species that eventually expel the metal core. 

In an interesting twist on the solvent free reaction, Petrukhina and coworkers co-sublimed a volatile metal complex, [Rh2(CF3C02)4], and arene molecules including paracyclophanes to yield organometallic coordination polymers. Moderate yields of crystalline products were obtained (35-70%),... 

---