The oxidation of six charged iron( 111) tetraarylporphyrins with chemical oxidants has been investigated. In aqueous solution each can be converted by tert-butyl hydroperoxide or monopersulphate into its corresponding oxoiron( iv) porphyrin, whereas in methanol only the iron (111) tetra (N-methylpyridyl) porphyrins form detectable ferryl porphyrins at ambient temperatures.On standing, the iron species revert to the parent porphyrin with a small loss due t o non-reversible oxidative destruction. That the oxidised porphyrin intermediates are oxoiron (iv) species has been determined using UV-VIS, resonance Raman, 'H NMR and EPR spectroscopy.The mechanism of formation of the ferryl porphyrins and the factors that influence their stability are examined and discussed. I n particular steric effects and to a lesser extent electron-withdrawing substituents are shown to be important in stabilising the iron(iv) species. These effects are explained in terms of their influence on the disproportionation of two ferryl species into an iron(iii) porphyrin and an iron(iv) porphyrin K radical cation.Paper 0/04944A

Four tetraaryl metalloporphyrin catalysts [ FeY Ar = phenyl and pentafluorophenyl; Feu' and Mn"', Ar = 2.6-dichlorophenyl (Fe'TDCPP and Mn"TOCPP)] have been coordinatively bonded to poly(4-vinylpyridine), and imidazole modified polystyrene ( PS-lm) and silica (Si-lm). Evidence is presented that suggests that the iron( 111) porphyrins are predominantly bis-ligated to the polymer supports whereas with MnTDCPP mono-ligation is preferred. On Si-lm all the complexes are mono-ligated. A fifth metalloporphyrin, the ionic manganese(tt1) 5.1 0.1 5,20-tetra(N-methyl-4-pyridyl)porphyrin (Mn"'T4M PyP), which binds strongly to unmodified silica, does not ligate to Si-lm.Leaching experiments show that FeiiiTDCPP is most strongly anchored to the supports. The resulting materials have been used as catalysts for the oxidation of cyclohexene and cyclooctene by iodosylbenzene. The oxidant accountabilities are good and product distributions from reactions under nitrogen are very comparable to those from analogous homogeneous oxidations. However, the rates of the former are markedly lower. Oxidations of cyclohexene, but not of cyclooctene, in air are biphasic. The first phase, where epoxidation predominates, is attributable to an Feii'TDCPPcatalysed oxidation by PhlO and the second, which leads to allylic oxidation, to radical autoxidation.The best catalysts for large turnover epoxidations are FeI'lTDCPP and Mnii'TDCPP on Si-lm. The causes of the lower yields with catalysts on the more flexible polymer supports are discussed.A limited study with H202 as the oxidant reveals that Mn"'T0CPP on Si-lm, in contrast to the ionic MnmT4M PyP on silica, catalyses the epoxidation of cyclooctene. 104 112 55 98 135 640 ' 655 ' 309 1125' 675 735 126 349 116 No Yes No No Yes No No Yes No No No No No No a Supported catalyst (100 mg), (Z)-cyclooctene (0.3 cm3), PhIO (30 mg), solvent (3 an3). Loading of metalloporphyrin on support/mg g-'. Turnovers calculated on epoxide yield. Oxidation with a second addition of PhIO. Total product Solvents: methanol (M); dichloromethane (D); and acetonitrile (A). Monitored by UV-VIS spectroscopy of reaction solution. Based on PhIO after 24 h. Not determined. yields from five additions of PhIO, interval between additions 24 h. Paper 4/0 1845A

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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.