Influence of Perfluorinated End Groups on the SFRD of [Pt(cod)Me(CnF2n+1)] onto Porous Al2O3 in CO2 under Reductive Conditions

The optimized synthesis of a range of cyclooctadiene-stabilized Pt complexes that contained different perfluoro-alkane chains, [Pt(cod)Me(CnF2n+1)], is presented. These metal-organic compounds were employed in the so-called supercritical fluid reactive deposition (SFRD) in CO2 under reductive conditions to generate metallic nanoparticles on aluminum oxide as a porous support. Thus, Al2O3-supported Pt nanoparticles with a narrow particle-size distribution were obtained. At a reduction pressure of 15.5MPa and a temperature of 353K, particle diameters of d(50)=2.3-2.8nm were generated. Decreasing the pressure during the reduction reaction led to slightly larger particles whilst decreasing the amount of organometallic precursor in CO2 yielded a decrease in the particle size from x(50)=3.2nm to 2.6nm and a particle-size distribution of 2.2nm. Furthermore, substitution of the CH3 end group by the CnF2n+1 end groups led to a significant drop in Pt loading of about 50%. Within the series of perfluorinated end groups that were considered, the Pt complex that contained a branched perfluoro-isopropyl group showed the most-interesting results when compared to the control precursor, [Pt(cod)Me-2] (1).