Models of siroheme and sirohydrochlorin. pi. cation radicals of iron(II) isobacteriochlorin

Journal Article · Wed Jan 16 04:00:00 EST 1980 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00522a073· OSTI ID:5373895

Chang, C K ^[1]; Fajer, J

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1. Michigan State Univ., East Lansing

Due to the difficulties associated with obtaining the quantities of microbial siroheme needed for extensive studies, preparation of a synthetic iron complex of the isobacteriochlorin family reported here is noteworthy. Hydrogen peroxide reacted with octaethylporphyrin in 82% H/sub 2/SO/sub 4/ at 10/sup 0/C using excess H/sub 2/O/sub 2/ resulted in an overall yield of the porphyrin diketones in excess of 20%. The gemini-diketoporphyrin isolated by chromatography was converted to the methylated isobacteriochlorin by reaction with methyl lithium followed by hydrolysis. Reduction of the resultant tertiary alcohols yielded diasteric isomers of 2,4-dimethyl-gemini-octaethylisobacteriochlorin (I) which could not be separated by liquid chromatography. Reaction of this compound with ferrous perchlorate in pyridine-acetic acid medium under argon yielded, almost quantitatively, the violet pyridine hemechrome. Voltammetry, controlled potential coulometry, and EPR were used to examine the redox chemistry of I. Results indicated that the reacting species are ..pi.. cation radicals and that facile oxidation of the isobacteriochlorins dictates the choice of electron pathway involving the ..pi.. system in sulfite and nitrite reduction. (BLM)

• DOE Contract Number: EY-76-C-02-0016
• OSTI ID: 5373895
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 102:2; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

550200* -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
CARBOXYLIC ACIDS
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COMPLEXES
DATA
DATA FORMS
ENZYMES
EXPERIMENTAL DATA
HEME
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
INFORMATION
IRON COMPLEXES
ISOLATED VALUES
NITRITES
NITROGEN COMPOUNDS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDOREDUCTASES
OXYGEN COMPOUNDS
PIGMENTS
PORPHYRINS
REDUCTION
SULFITES
SULFUR COMPOUNDS
SYNTHESIS
TRANSITION ELEMENT COMPLEXES