Chromium corroles in four oxidation States.

We have isolated and characterized chromium complexes of 5,10,15-tris(pentafluorophenyl)corrole [(tpfc)H(3)] (1) in four oxidation states: [(tpfc(*))CrO][SbCl(6)] (6); [(tpfc)CrO] (2); [(tpfc)CrO][Cp(2)Co] (4); and [(tpfc)Cr(py)(2)] (3). Complex 6 was prepared both by electrochemical and chemical oxidation of 2; its formulation as a Cr(V)O ligand-radical species is based on UV-visible absorption as well as EPR measurements. Cobaltocene reduction of 2 gave 4; it was identified as a diamagnetic d(2) Cr(IV)O complex from its sharp (1)H NMR spectrum. Reaction of 2 with triphenylphosphine yielded a chromium(III) corrole, [(tpfc)Cr(OPPh(3))(2)] (5). Owing to its air sensitivity, 5 could not be isolated in the absence of excess OPPh(3). The structure of the Cr(III) bis-pyridine complex (3) was determined by X-ray crystallography (Cr-N distances: 1.926-1.952 A, pyrrole; 2.109, 2.129 A, pyridine).

Synthesis and characterization of germanium, tin, phosphorus, iron, and rhodium complexes of tris(pentafluorophenyl)corrole, and the utilization of the iron and rhodium corroles as cyclopropanation catalysts.

The germanium(IV), tin(IV). and phosphorus(v) complexes of tris(pentafluorophenyl)corrole were prepared and investigated by electrochemistry for elucidation of the electrochemical HOMO-LUMO gap of the corrole and the spectroscopic characteristics of the corrole pi radical cation. This information was found to be highly valuable for assigning the oxidation states in the various iron corroles that were prepared. Two iron corroles and the rhodium(I) complex of an N-substituted corrole were fully characterized by X-ray crystallography and all the transition metal corroles were examined as cyclopropanation catalysts. All iron (except the NO-ligated) and rhodium corroles are excellent catalysts for cyclopropanation of styrene, with the latter displaying superior selectivities. An investigation of the effect of the oxidation state of the metal and its ligands leads to the conclusion that for iron corroles the catalytically active form is iron(III), while all accesible oxidation states of rhodium are active.

First syntheses and X-ray structures of a meso-alkyl-substituted corrole and its Ga(III) complex.

The solvent-free condensation of heptafluorobutanal and pyrrole leads to the corresponding meso-alkyl-substituted corrole, which was metallated by gallium chloride to provide the first first-row non-transition-metal corrole. Both the ligand and the complex were characterized by X-ray crystallography.