Fluorous Zirconocene(IV) Complexes and Their Olefin Polymerization Activity in Toluene and Fluorous Biphasic Solvent Systems<sup>†</sup>

The synthesis (<b>4a</b>−<b>d</b>) and structure (<b>4a</b>,<b>c</b>) of the four crystalline, water-stable, hydrocarbon- and perfluorocarbon (PFC)-soluble fluorous zirconocene(IV) dichloride precatalysts [Zr{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub><sub>-</sub><i><sub>n</sub></i>(R<sub>F</sub>)<i><sub>n</sub></i>}<sub>2</sub>Cl<sub>2</sub>] (<i>n</i> = 1, R<sub>F</sub> = CH<sub>2</sub>CH<sub>2</sub>C<sub>6</sub>F<sub>13</sub> (<b>4a</b>), C<sub>8</sub>F<sub>17</sub> (<b>4b</b>), CH<sub>2</sub>C<sub>6</sub>F<sub>5</sub> (<b>4c</b>); <i>n</i> = 3, R<sub>F</sub> = CH<sub>2</sub>C<sub>6</sub>F<sub>5</sub> (<b>4d</b>)), possessing one to three fluorous alkyl or aryl groups attached to the cyclopentadienyl ligand through a silicon atom and an additional methylene (<b>4c</b>,<b>d</b>) or ethylene (<b>4a</b>) spacer or no spacer at all (<b>4b</b>), are reported. A nonfluorous analogue of <b>4a, </b>[Zr{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>SiMe<sub>2</sub>C<sub>8</sub>H<sub>17</sub>}<sub>2</sub>Cl<sub>2</sub>] (<b>4e</b>), was prepared for comparison, and <b>4a </b>was easily converted to its dimethyl derivative [Zr{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>SiMe<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>C<sub>6</sub>F<sub>13</sub>}<sub>2</sub>Me<sub>2</sub>] (<b>5a</b>). The ethylene polymerization activities of the zirconocene dichlorides were compared to those of the known bis{(trimethylsilyl)cyclopentadienyl}zirconium dichloride [Zr{η<sup>5</sup>-C<sub>5</sub>H<sub>4</sub>SiMe<sub>3</sub>}<sub>2</sub>Cl<sub>2</sub>] (<b>4f</b>), in both toluene and fluorous biphasic solvent (FBS) systems. In the case of <b>4b </b>a PE with a bimodal molecular weight distribution and a significantly lower molecular weight was obtained. Polymerization data and polymer properties for <b>4a</b>−<b>d</b>, compared to data for <b>4f</b>, show a marked influence of the fluorous groups and the alkyl spacer (e.g. methylene in <b>4c</b> or ethylene in <b>4a</b>). FBS conditions result in PE with a higher average molecular weight. Evidence on the nature of the active species formed when these precatalysts were treated with an excess of methylaluminoxane (MAO) is presented.