Electron Transfer Chemistry of Organometallic Porphyrins

1997 Fiscal Year Final Research Report Summary

• Project/Area Number: 08044083
• Research Category: Grant-in-Aid for international Scientific Research
• Allocation Type: Single-year Grants
• Section: Joint Research
• Research Field: 物質変換
• Research Institution: Osaka University
• Principal Investigator: FUKUZUMI Shunichi Osaka University, Faculty of Engineering, Professor, 工学部, 教授 (40144430)
• Co-Investigator(Kenkyū-buntansha): KADISH Karl M. University of Houston, Department of Chemistry, Professor, 化学科, 教授 ; SUENOBU Tomoyoshi Osaka University, Faculty of Engineering, Research Associate, 工学部, 助手 (90271030) ; ITOH Shinobu Osaka University, Faculty of Engineering, Associate Professor, 工学部, 助教授 (30184659)
• Project Period (FY): 1996 – 1997
• Keywords: Organometallics / Porphyrin / Electron Transfer / Redox Potential / Migration Reaction / Oxidation / ESR / Axial Ligand Coordination

Research Abstract

The one-electron oxidation of alkyl and aryl metal sigma-bonded porphyrins is often followed by a metal to nitrogen migration of the sigma-bonded organic ligand. Several studies of oxidized cobalt sigma-bonded porphyrins have suggested that a Co^<III> pi cation radical rather than a Co^<IV> cation is generated prior to the migration.
The present study combines the use of electrochemistry, UV-vis and ESR spectroscopy and stopped flow kinetics to investigate the reactions and properties of singly oxidized organoporphyrins of the type (P) M (R) and (P) M (R)(L) where P = the dianion of substituted porphyrins : TPP or OEP,M = Co or Fe, R = n-Bu, Et, Me or Ph, L = acetonitrile or a substituted pyridine. The results of our studies show clearly that a (TPP) Co^<IV> (R) complex can be generated under specific solution conditions and the cleavage of the cobalt-carbon bond occurs via a rate-determining intramolecular electron transfer from R to Co and this results in a metal to nitrogen migration of the R group. In a similar mannar, one-electron oxidation of an aryl sigma-bonded iron porphyrin, (OEP) Fe^<III> (R) results in the formation of an Fe^<IV> center which is invariably generated prior to migration.

Research Products

• [Publications] Shunichi Fukuzumi et al.: "Electron Transfer Mechanism of Organocobalt Porphyrins.Site of Electron Transfer,Migration of Organic Groups,and Cobalt-Carbon Bond Energies in Different Oxidation States" J.Am.Chem.Soc.(印刷中). (1998)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Shunichi Fukuzumi et al.: "Kinetic and Thermodynamic Studies of Iron(III) and Iron(IV) Sigma Bonded Porphyrins.Formation and Reactivity of[(OEP)Fe(R)]^<n+> where OEP is the Dianion of Octaethylporphyrin,n=0,1,2,3 and R=C_6H_5,3,4,5-C_6F_3H_2,2,4,6-C_6F_3H_2,_6F_4HorC_6F_5" Inorg.Chem.(印刷中). (1998)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Shunichi Fukuzumi et al.: "Mechanistic Studies of Aliphatic Ligand Hydroxylation of a Copper Complex by Dioxygen:A Model Reaction for Copper Monooxygenases" J.Am.Chem.Soc.120・(印刷中). (1998)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Shunichi Fukuzumi et al.: "Modeling of the Chemistry of Quinoprotein Methanol Dehydrogenase.Oxidation of Methanol by Calcium Complex of Coenzyme PQQ via Addition-Elimination Mechanism." J.Am.Chem.Soc.119・2. 439-440 (1997)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Shunichi Fukuzumi et al.: "Direct Observation of Radical Intermediates Derived from Thiamin Coenzyme Models and the Redox Behavior" Angew.Chem.,Int.Ed. 37・(印刷中). (1998)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Shunichi Fukuzumi et al.: "Model Studies of Calcium-containing Quinoproteins Alcohol Dehydrogenaes.Catalytic Role of Ca^<2+> for the Oxidation of Alcohols by Coenzyme PQQ" Biochemistry. (印刷中). (1998)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Shunichi Fukuzumi et al.: "Advances in Photochemistry" Wiley(New York)(印刷中), (1998)
  • Description: 「研究成果報告書概要(和文)」より
• [Publications] Shunichi Fukuzumi et al.: "Electron Transfer Mechanism of Organocobalt Porphyrins. Site of Electron Transfer, Migration of Organic Groups, and Cobalt-Carbon Bond Energies in Different Oxidation State" J.Am.Chem.Soc.(in press). (1998)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Shunichi Fukuzumi et al.: "Kinetic and Thermodynamic Studies of Iron (III) and Iron (IV) Sigma Bonded Porphyrins. Formation and Reactivity of [(OEP)Fe(R)]^<n+> where OEP is the Dianion of Octaethylporphyrin, n = 0, l, 2,3 and R = C_6H_5,3,4,5-C_6F_3H_2,2,4,6-C_6F_3H_2, C_6F_4H or C_6F_5" Inorg.Chem. (in press). (1998)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Shunichi Fukuzumi et al.: "Mechanistic Studies of Aliphatic Ligand Hydroxylation of a Copper Complex by Dioxygen : A Model Reaction for Copper Monooxygenases" J.Am.Chem.Soc.120 (in press). (1998)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Shunichi Fukuzumi et al.: "Modeling of the Chemistry of Quinoprotein Methanol Dehydrogenase. Oxidation of Methanol by Calcium Complex of Coenzyme PQQ via Addition-Elimination Mechanism" J.Am.Chem.Soc.119(2). 439-440 (1997)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Shunichi Fukuzumi et al.: "Direct Observation of Radical Intermediates Derived from Thiamin Coenzyme Models and the Redox Behavior" Angew.Chem.110 ; , 37 (in press). (1998)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Shunichi Fukuzumi et al.: "Model Studies of Calcium-containing Quinoproteins Alcohol Dehydrogenaes. Catalytic Role of Ca^<2+> for the Oxidation of Alcohols by Coenzyme PQQ" Biochemistry. (in press). (1998)
  • Description: 「研究成果報告書概要(欧文)」より
• [Publications] Shunichi Fukuzumi et al.: "Catalysis of Photoinduced Electron Transfer Reactions, Advances in Photochemistry. ed.by D.C.Neckers, Wiley, New York, (in press), (1998)
  • Description: 「研究成果報告書概要(欧文)」より