Six silicas, with different surface areas, pore sizes and pore volumes, have been surface modified with pyridine groups and used t o support iron( 111) 5.1 0,15,2O-tetra(2,6-dichlorophenyl) porphyrin (Fe'I'TDCPP) by ligation t o the metal ion. Comparison of these materials (SiPy-Fe'I'TDCPP) as catalysts for the epoxidation of (Z) -cyclooctene by iodosylbenzene in dichloromethane reveals that all have essentially the same catalytic activity and that the heterogeneous reactions are significantly slower (ca. ten-fold) than the homogeneous analogue. In small scale repeat-use experiments the catalysts achieve 2200 catalyst turnovers without loss of activity, however, larger scale reactions (7900 turnovers) lead t o catalytic oxidative bleaching and > 50% reduction in activity.A Hammett study of the epoxidation of styrene and 4-substituted styrenes gives p values (vs. a ' ) of -0.95 and -0.98 for oxidations catalysed b y FelIlTDCPP and a supported catalyst SiPy-Fe"'TDCPP, respectively. The similarity of these values t o each other and to values from other iron( 111) porphyrin-catalysed epoxidations is discussed. A minor pathway in the oxidation of the styrenes in air that leads t o benzaldehydes is attributed t o dioxygen intercepting an intermediate in the reaction.

Iron(II1) tetra(pentafluoropheny1)-and tetra(2,6-dichlorophenyl)-porphyrin (FeTPFPP and FeTDCPP) have been co-ordinatively bound to imidazole and pyridine groups on organic polymers (PSIm and PVP) and on the surface of silica (SiIm and SiPy). The oxidation and spin states of the resulting supported catalysts have been characterised by UV-VIS, resonance Raman and EPR spectroscopy. Evidence is presented that the iron porphyrins on the flexible organic polymers are all low-spin his-ligated iron(r1) species. In contrast, on the rigid modified silicas the iron porphyrins are mono-ligated and high spin. Furthermore whereas FeTDCPP on SiIm is an iron(111) species, on SiPy it is iron(r1) and FeTPFPP on SiIm is a mixture of both oxidation states.