Photoactivation of Polymer-Anchored Catalysts: Iron Carbonyl-Catalyzed Reactions of Alkenes.

Abstract : Photoactivation of polymer-anchored iron carbonyl catalysts is reported. Prototypic reactions are 1-pentene isomerization and reaction of 1-pentene with HSiEt3 which can be photocatalyzed at 25 C by near-uv irradiation of suspensions of the polymer-anchored catalyst systems. The basic polymer system is a styrene/1% divinylbenzene resin derivatized either with -PPh2 or -P(Ph)CH2CH2PPh2 anchoring sites for catalyst precursors. Fe(CO)n (n = 3,4) are attached to the phosphine sites by reaction with Fe3(CO)12. The polymer-anchored catalysts show turnover numbers exceeding 20000 in some cases, and observed quantum yields exceed unity, evidencing the photogeneration of a thermal catalyst. The data allow the conclusion that the anchoring Fe-P bond is relatively photoinert and that the catalysis is initiated by the photoinduced dissociation of CO from the Fe(CO)n moieties. The catalytic chemistry for the polymer systems parallels that found using homogeneous Fe(CO)n(PPh3)5-n (n = 3,4) model photochemical catalyst precursors. (Author)