Highly Metallized Polymers:  Synthesis, Characterization, and Lithographic Patterning of Polyferrocenylsilanes with Pendant Cobalt, Molybdenum, and Nickel Cluster Substituents

High molecular weight, soluble, air- and moisture-stable, highly metallized (>25 wt% metal) polyferrocenylsilanes (PFS) [Fe(η-C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Si(Me){Co<sub>2</sub>(CO)<sub>6</sub>C<sub>2</sub>Ph}]<i><sub>n</sub></i> (<b>Co</b><b>−</b><b>PFS</b>), [Fe(η-C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Si(Me){Mo<sub>2</sub>Cp<sub>2</sub>(CO)<sub>4</sub>C<sub>2</sub>Ph}]<i><sub>n</sub></i> (<b>Mo</b><b>−</b><b>PFS</b>), and [Fe(η-C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Si(Me){Ni<sub>2</sub>Cp<sub>2</sub>C<sub>2</sub>Ph}]<i><sub>n</sub></i> (<b>Ni</b><b>−</b><b>PFS</b>) containing pendant cobalt, molybdenum, and nickel clusters, respectively, have been prepared via macromolecular clusterization of an acetylide-substituted PFS [Fe(η-C<sub>5</sub>H<sub>4</sub>)<sub>2</sub>Si(Me)C⋮CPh]<i><sub>n</sub></i> with [Co<sub>2</sub>(CO)<sub>8</sub>], [{MoCp(CO)<sub>2</sub>}<sub>2</sub>], or [{NiCp(CO)}<sub>2</sub>]. The extent of clusterization achieved was in the range of 70−75%. All three highly metallized polymers were demonstrated to function as negative-tone resists in electron-beam lithography, while <b>Co</b><b>−</b><b>PFS</b> and <b>Mo</b><b>−</b><b>PFS</b> were successfully patterned by UV−photolithography, allowing the fabrication of micron-sized bars, dots, and lines. These studies suggest that the highly metallized polymers may be useful in the fabrication of patterned arrays of alloy nanoparticles for both materials science and catalytic applications.