Electron-transfer reactions of 17-electron and 19-electron organometallic radicals, CpW(CO)[sub 3] and CpW(CO)[sub 3]PPh[sub 3]

Journal Article · Fri Oct 01 00:00:00 EDT 1993 · Organometallics; (United States)

DOI:https://doi.org/10.1021/om00034a048· OSTI ID:5576229

Scott, S L; Espenson, J H; Chen, W J ^[1]

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1. Ames Lab., IA (United States) IOWA State Univ., Ames, IA (United States)

Laser flash photolysis of [CpW(CO)[sub 3]][sub 2] was carried out at 490 nm, where the primary photoprocess gives a 17-electron radical, CpW(CO)[sub 3]. The metal radical acts as both an electron donor and acceptor. The radical reduces ferrocenium ions (k = [1.89(4)] [times] 10[sup 7] L mol[sup [minus]1] s[sup [minus]1]) and benzoquinone (k = [2.7(1)] [times] 10[sup 7] L mol[sup [minus]1] s[sup [minus]1]) at 23[degrees]C in acetonitrile. Triphenylphosphine accelerates the reaction of the tungsten radical with ferrocenium ions, suggesting the formation of the more strongly reducing 19-electron radical CpW(CO)[sub 3]PPh[sub 3]. It reacts with ferrocenium ions; k = 3 [times] 10[sup 9] L mol[sup [minus]1] s[sup [minus]1]. The base-induced disproportionation of CpW(CO)[sub 3] was used to evaluate binding constants for CpW(CO)[sub 3] and PPh[sub 3] (K = 6 [+-] 1 L mol[sup [minus]1]) and pyridine (K = 0.16 [+-] 0.04 L mol[sup [minus]1]). Also, the CpW(CO)[sub 3] radical oxidizes decamethylferrocene (2.2 [times] 10[sup 8] L mol[sup [minus]1] s[sup [minus]1]) and N,N,N[prime],N[prime]-tetramethylphenylenediamine (2.6 [times] 10[sup 7] L mol[sup [minus]1] s[sup [minus]1]). In this system there is a secondary process responsible for the re-reduction of TMPD[sup [center dot]+]. We suggest the rapid formation of the radical anion [CpW(CO)[sub 3]][sub 2][sup [center dot][minus]], presumed to be a powerful electron donor, to account for back-electron transfer, but this has not been proved. 36 refs., 4 figs.

• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5576229
• Journal Information: Organometallics; (United States), Journal Name: Organometallics; (United States) Vol. 12:10; ISSN ORGND7; ISSN 0276-7333
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
400500 -- Photochemistry
CARBONYLS
CATALYSTS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPLEXES
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELECTRON TRANSFER
KINETICS
LASER RADIATION
ORGANIC COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
RADIATIONS
RADICALS
REACTION KINETICS
TRANSITION ELEMENT COMPLEXES
TUNGSTEN COMPLEXES