Electron transfer reactions of the organometallic free radical CpMo(CO){sub 3} with triphenylpyrylium ion and triphenylpyranyl radical
- Ames Lab., IA (United States)
The title compound, a 17-electron organometallic free radical, undergoes reversible electron transfer in two steps in acetonitrile. It is oxidized by the triphenylpyrylium ion (TPP{sup +}) to [CpMo(CO){sub 3}NCCH{sub 3}]{sup +} and reduced by TPP to [CpMo(CO){sub 3}]{sup -}. Three of the four rate constants for the forward and reverse directions of these two steps were evaluated directly by flash photolysis and stopped-flow techniques. The results were considered in light of data for similar reactions of [CpMo(CO){sub 3}]{sup +} with TMPD-{sup +} and TMPD (TMPD = N,N,N{prime},N{prime}-tetramethyl-1,4-phenylenediamine). Notable differences were found, due entirely to the 0.55 V difference in E{degree} for the two A{sup -}/A couples. On the other hand, surprising agreement was found between the rate constants for a pair of reactions that differ by 10{sup 8} in their equilibrium constants. Both of these rate constants are at the diffusion-controlled level. We thus conclude that the minor species [CpMo(CO){sub 3}-NCCH{sub 3}]{sup +} (sometimes referred to as a 19e radical), the binding constant of which is only approximately 10{sup -4} L mol{sup -1}, may carry the diffusion-controlled reactions with TPP{sup +} and TMPD{sup +}. Reduction to the 18e molybdenum anion, however, does not proceed with the involvement of the coordinated solvent. 26 refs., 3 figs., 2 tabs.
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 106755
- Journal Information:
- Organometallics, Journal Name: Organometallics Journal Issue: 9 Vol. 14; ISSN ORGND7; ISSN 0276-7333
- Country of Publication:
- United States
- Language:
- English
Similar Records
Solvent effects in the reactions of peroxyl radicals with organic reductants. Evidence for proton-transfer-mediated electron transfer
Rapid hydration of the acetyl radical. A pulse radiolysis study of acetaldehyde in aqueous solution