Comparison of the Photocatalytic Behavior of Phosphinated Polymer-Anchored Iron Carbonyl Species and Homogeneous Phosphine Substituted Iron Carbonyl Species: Alkene Isomerization and Reaction with Trialkylsilanes

A styrene-1% divinylbenzene resin whose phenyl rings have been derivatized with PPh2 groups serves as an “anchor” for Fe(CO)n (n=3, 4) groups; the anchor is the Fe-P bond. The photocatalytic activity of suspensions of the polymer-anchored Fe(CO)n has been compared to that of homogeneous solutions of Fe(CO)n(PPh3)5-n (n=3-5). 1-Pentene isomerization and reaction with HSiEt3 can be affected with each system. Observed quantum yields for 1-pentene isomerization exceed unity for each catalyst precursor, and the initial tram- to cis-2-pentene ratio depends on the catalyst precursor, implicating the retention of the triarylphosphine groups in the actual catalytically active species. Irradiation of Fe(CO)n(PPh3)5-n (n=4) results in loss of CO, not PPh3, suggesting a photoinert anchor to the Fe(CO)n groups in the polymer systems. These experiments establish the viability of photogenerating catalysts anchored to polymer supports without destruction of the anchor bond in the photogeneration procedure.