title: Metal complexes of meso-amino-octaethylporphyrin and the oxidation of NiII(meso-amino-octaethylporphyrin).
abstract: The crystal structures of meso-NH2-OEPH2, NiII(meso-NH2-OEP), and CuII(meso-NH2-OEP) (where OEP is the dianion of meso-amino-octaethylporphyrin) have been determined to examine the effects of the meso-substituent on the geometry of the ligand. CuII(meso-NH2-OEP) has a nearly planar geometry while the free ligand itself and NiII(meso-NH2-OEP) have ruf conformations. NiII(meso-NH2-OEP) is much less reactive toward oxidation than are (py)2FeII(meso-NH2-OEP), ClFeIII(meso-NH2-OEP), or NiII(meso-HO-OEP), which all undergo oxidation in pyridine solution when exposed to dioxygen. Treatment of NiII(meso-NH2-OEP) with iron(III) chloride in chloroform solution does result in oxidation of the ligand in two separate processes. One involves oxygenation at the trans-meso position, while the other results in ring cleavage and removal of the amino function. The open-chain tetrapyrrole complex, NiII(OEB-CO2Et), has been characterized by single-crystal X-ray diffraction and shown to contain a helical ligand with a four-coordinate nickel ion.
authors.affiliation: Department of Chemistry, University of California, Davis, California 95616, USA.
authors.forename: Natasza
authors.initials: N
authors.lastname: Sprutta
authors.forename: Sankar Prasad
authors.initials: SP
authors.lastname: Rath
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Olmstead
authors.forename: Alan L
authors.initials: AL
authors.lastname: Balch
mesh_terms: D003300:Copper / Q000737:chemistry; D018360:Crystallography, X-Ray; D005296:Ferrous Compounds; D008968:Molecular Conformation; D015394:Molecular Structure; D009532:Nickel / Q000737:chemistry*; D010084:Oxidation-Reduction; D011166:Porphyrins / Q000737:chemistry*; D011725:Pyridines
chemical_list: D005296:Ferrous Compounds; D011166:Porphyrins; D011725:Pyridines; C500486:meso-amino-octaethylporphyrin; D003300:Copper; D009532:Nickel; C029451:ferrous chloride