Oxidative homolysis reactions between organochromium macrocycles and dihalide radical anions

Journal Article · Wed Nov 13 04:00:00 EST 1991 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00023a036· OSTI ID:7274067

Shi, Shu; Espenson, J H ^[1]; Meyerstein, D ^[2]; Meisel, D ^[3]

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1. Iowa State Univ., Ames (United States)
2. Ben-Gurion Univ. of the Negev, Beer-Sheva (Israel)
3. Argonne National Lab., IL (United States)

Many electron acceptors are able to oxidize organometals. In the case of organochromium(III) complexes such as (H{sub 2}O){sub 5}CrR{sup 2+} and RCrL(H{sub 2}O){sup 2+} (L = (15)aneN{sub 4} = 1,4,8,12-tetraazacyclopentadecane), studies of the oxidation step have been examined for the acceptors Ru(bpy){sub 3}{sup 3+}, {sup 2}E-Cr(bpy){sub 3}{sup 3+}, Ni((14)aneN{sub 4}){sup 3+}, and IrCl{sub 6}{sup 2{minus}}. As a result of the reaction between R{sm bullet} and I{sub 2}, I{sm bullet} is formed and thus I{sub 2}{sup {sm bullet}{minus}}. The form of the rate law for the reaction between I{sub 2} and RCrL(H{sub 2}O){sup 2+} allowed us to infer that one of the chain-propagating steps was the oxidation of the organometal by I{sub 2}{sup {sm bullet}{minus}}. The study of the I{sub 2} reaction did not give a value of this rate constant, because k for the chain reaction is a composite that contains also the rate constants for the initiation and termination steps. The authors decided to investigate the reaction involving I{sub 2}{sup {sm bullet}{minus}} for several reasons. First, they wanted to confirm that such a reaction occurs rapidly enough for it to be a chain propagation step in the iodine reaction. Second, they wanted to use its rate constant, in conjunction with the observed constant for the chain reaction, to calculate the rate constant for other elementary steps in the chain. Third, by variation of the group R and by use of other X{sub 2}{sup {sm bullet}{minus}} radicals, they sought to learn more about the nature of the rate-determining step in the reaction. The point behind the use of the macrocycle is that, in donating considerable electron density to the metal, is assists oxidative pathways (for X{sub 2} and X{sub 2}{sup {sm bullet}{minus}}) and decreases solvolytic and homolytic decomposition pathways.

• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 7274067
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 30:23; ISSN 0020-1669; ISSN INOCA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ANIONS
ANTITHYROID DRUGS
BEAMS
BINDING ENERGY
CARBONIC ACID DERIVATIVES
CHALCOGENIDES
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHROMIUM COMPLEXES
COMPLEXES
DECOMPOSITION
DRUGS
ELECTRON BEAMS
ELECTRONS
ELEMENTARY PARTICLES
ENERGY
ENERGY RANGE
FERMIONS
HALIDES
HALOGEN COMPOUNDS
HORMONE ANTAGONISTS
HYDROXYL RADICALS
IONS
KINETICS
LEPTON BEAMS
LEPTONS
MEV RANGE
MEV RANGE 10-100
NITROGEN COMPOUNDS
NITROGEN OXIDES
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANOMETALLIC COMPOUNDS
OXIDATION
OXIDES
OXIDIZERS
OXYGEN COMPOUNDS
PARTICLE BEAMS
QUANTITY RATIO
RADIATION EFFECTS
RADICALS
RADIOLYSIS
REACTION KINETICS
THIOCYANATES
TRANSITION ELEMENT COMPLEXES
VALENCE