Radiolytic studies of the redox reactions of ruthenium porphyrins
Oxidation of Ru{sup II} porphyrins to the Ru{sup III} and Ru{sup IV} states and ligand-exchange reactions of the various states have been studied by radiolytic methods. Ru{sup II} porphyrins, stabilized with a CO ligand, undergo one-electron oxidation on the porphyrin ring to form the {pi}-radical cation. When Ru{sup II}(P)(CO) (P = octaethylporphyrin or tetraphenylporphyrin) is oxidized by irradiation in CH{sub 2}Cl{sub 2}, the initial radical cation combines with Cl{sup {minus}}, formed by radiolysis of the solvent or added beforehand, with a rate constant of about 1 {times} 10{sup 5} M{sup {minus}1} s{sup {minus}1} to yield Ru{sup II}(P{sup {sm bullet}+})(CO)(Cl{sup {minus}}). Irradiation of the same porphyrins in acetonitrile results not in oxidation but rather in uptake of the CN{sup {minus}} produced by the radiolysis to form Ru{sup II}P(C)(CN{sup {minus}}). When this product is oxidized by irradiation in acetonitrile/CCl{sub 4} solutions, oxidation occurs first on the ligand to form Ru{sup II}(P{sup {sm bullet}+})(CO)(CN), which is unstable and transforms into Ru{sup III}P(CN{sup {minus}}){sub 2} as the final product, with a rate constant of 4.5 {times} 10{sup 3} s{sup {minus}1}. The Ru{sup IV} state exists mainly as the {mu}-oxo dimer, which was produced by radiolysis of Ru{sup II}(CO) in CH{sub 2}Cl{sub 2} saturated with KOH. The product, ((HO)Ru{sup IV}P){sub 2}O, undergoes a gradual exchange of the OH groups with one and then two chlorides upon radiolysis in CH{sub 2}Cl{sub 2} as was demonstrated by the spectral changes. Chemical redox reactions were carried out to complement the radiolysis results.
- OSTI ID:
- 7071544
- Journal Information:
- Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:6; ISSN 0022-3654; ISSN JPCHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
400600* -- Radiation Chemistry
ABSORPTION SPECTROSCOPY
ACETONITRILE
BEAMS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CARBOXYLIC ACIDS
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISTRY
COBALT 60
COBALT ISOTOPES
COMPLEXES
DATA
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELECTRON BEAMS
ENERGY RANGE
EXPERIMENTAL DATA
GAMMA RADIATION
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IONIZING RADIATIONS
IRRADIATION
ISOMERIC TRANSITION ISOTOPES
ISOTOPES
KINETICS
LEPTON BEAMS
MEV RANGE
MEV RANGE 01-10
MINUTES LIVING RADIOISOTOPES
NITRILES
NUCLEI
NUMERICAL DATA
ODD-ODD NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PARTICLE BEAMS
PORPHYRINS
PULSED IRRADIATION
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RADIOISOTOPES
RADIOLYSIS
REACTION KINETICS
REDOX REACTIONS
RUTHENIUM COMPLEXES
SPECTROSCOPY
TRANSITION ELEMENT COMPLEXES
YEARS LIVING RADIOISOT