Paul E. Ellis

Halogen substituent effects on the catalytic activity of iron porphyrin complexes for selective air-oxidation of alkanes in the liquid phase

Halogenation of the porphyrin ring of porphyrinatoiron(III) complexes greatly increases their catalytic activity for the selective mild reaction of alkanes with molecular oxygen. The greater the halogen content the greater is the catalytic activity of the complex. Selective reaction of isobutane and propane with molecular oxygen is catalyzed bytetrakis(pentafluorophenyl)porphyrinatoiron(III) azido, hydroxo, or halo complexes under mild conditions of temperature and pressure. No added co-reductant is required in these systems. Catalytic oxidation of isobutane in the presence oftetrakis (pentafluorophenyl)porphyrinatoiron(III) hydroxide at room temperature gavetert-butyl alcohol in 95% selectivity. The catalyst activity was virtually unchanged after over 140 hours at room temperature and over 12,000 turnovers (moles of alcohol produced/mole of metal complex used) of isobutane to the alcohol were observed.

Copper(II) and Nickel(II) Octabromo-tetrakis(pentafluorophenyl)Porphyrin Complexes

The copper and nickel complexes of 2,3,7,8,12,13,17, 18-octabromo-5,10,15,20-tetrakis(pentaftuorophenyl) porphyrin ({4,5,9,10,14,15,19,20-octabromo-2,7,12,17-tetrakis(pentaftuorophenyl)-21,22,23,24-tetraazapentacyclo[l6.2.1.1^(3,6).l^(8,11).l^(13,16)]tetracosa-l,3-(22),4,6,8(23),9,11,13(24),14,16,18(21),19-dodecaene }copper(II) 0.5-dichloromethane solvate and {4,5,9,10,14,15,19,20-octabromo-2,7,12,17-tetrakis(pentaftuorophenyl)-21,22,23,24-tetraazapentacyclo( 16.2.1.1^(3,6).l^(8,11).l^(13,16)]tetracosa-l,3(22),4,6,8(23),9,ll,13(24),14,16,18(21),19-dodecaene} nickel(II)0.5-dichloromethane solvate) form isostructural crystals. There is significant distortion from planarity of the porphyrin ring caused by the octabromo substituents interacting with the meso-pentafluorophenyl groups and with each other, with departures of the Br atoms from the plane defined by the four N atoms of up to 2.36 A. This tetrahedral distortion of the molecule does not result in any significant changes in bond distances from those in non-halogenated tetraphenylporphyrin complexes.

A highly solvated zinc(II) tetrakis(pentafluorophenyl)-β-octabromoporphyrin

The title compound, {4,5,9,10,14,15,19,20-octabromo-2,7,12,17-tetrakis(pentafluorophenyl)-21,22,23,- 24-tetraazapentacyclo[16.2.1.1^(3,6).1^(8,11).1^(13,16)]tetracosa-1,3(21),4,6,8(22),9,11,13(23),14,16,18(24),19-dodecaene }zinc(II) (carbon tetrachloride, o-dichlorobenzene, acetone, methanol, water solvate) has a large tetrahedral distortion, with the Br atoms as much as 1.83 A from the plane of the N atoms. The distortion affects primarily bond angles and bond torsion angles; bond distances in the molecule are normal. Several different solvents are incorporated into the crystal, providing a close (2.16 A) O atom as an axial neighbor to Zn and a more distant (3.16 A) Cl atom, in the opposite axial site.

A μ-Oxo-bis[iron(III) porphyrin] Complex

Partial nitration of iron(III) 2,3,7,8,12,13,17,18-octaethylporphyrin chloride [Fe III (OEP)Cl] gives the μ-oxo-bis(5,15-dinitro) compound μ-oxo-bis[2,3,7,8,12,-13,17,18-octaethyl-5,15-dinitroporphyrinato)iron(III)], [Fe 2 (C 36 H 42 N 6 O 4 ) 2 O], which is similar to other μ-oxo-iron(III) porphyrin complexes but with less ruffling of the porphyrin structure. The porphyrin planes are not parallel [the angle between plane normals is 169 (2)°] and the Fe-O-Fe angle is 167.9(3)°. As expected, the Fe atoms are significantly displaced from the porphyrin planes towards the bridging O atom : 0.46 A for Fe1 and 0.49 A for Fe2. The two porphyrin residues are eclipsed with respect to their C atoms, but the nitro groups are staggered by 90° from one residue to the other.

Copper(II) tetrakis(pentafluorophenyl)-β-octachloroporphyrin

The title compound, {4,5,9,10,14,15,19,20-octachloro-2,7,12, 17-tetrakis(pentafluorophenyl)-20,22,23,24- tetraazapentacyclo[l6.2.l.1^(3·6).l^(8·11).l^(13·16)]tetracosa-1,3(21),4,6,8(22),9,11, 13(23), 14, 16, 18(24), 19-dodecaene}copper(II)(CuTFPPC1_8)dichloromethane solvate, shows a large tetrahedral distortion or ruffling, with pairs of Cl atoms alternately averaging + 1.20 and -1.18 A out of the plane of the four N atoms; the Cu atom is 0.01 A out of the plane and the N atoms show a slight (±0.12 A) tetrahedral distortion. A Cl atom of the solvent, at 3.515 (6) A in an approximately axial position, is the closest non-bonded neighbor of the Cu atom.

Effect of axial azide on the selective, low temperature metalloporphyrin-catalysed reactions of isobutane with molecular oxygen

Azido(tetraphenylporphyrinato) complexes of CrIII, MnIII, and FeIII catalyse selective, low temperature hydroxylation of isobutane with molecular oxygen and provide many turnovers in the absence of added co-reductants.

Effect of fluorination of the meso-phenyl groups on selective tetraphenylporphyrinatoiron(III)-catalysed reactions of propane with molecular oxygen

A series of tetrakis(pentafluorophenyl)iron(III) complexes are active catalysts for the selective air oxidation of propane to isopropyl alcohol and acetone under mild conditions, and provide hundreds of catalytic turnovers in the absence of any added co-reductants.

Novel iron meso-nitrooctaethylporphine complexes for the catalytic reaction of alkanes with molecular oxygen

Introducing nitro groups into themeso-positions of a metalloporphyrin converts a catalytically inactive complex into a highly active catalyst for the oxidation of alkanes with molecular oxygen. The degree of nitration correlates with both the Fe(III)/Fe(II) reduction potential and the catalytic activity.