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Reactions of the 17-electron bis(dimethylglyoximato)(triphenylphosphine)rhodium(II) radical

Journal Article · · Inorg. Chem.; (United States)
DOI:https://doi.org/10.1021/ic00291a020· OSTI ID:5852635
The indicated metal-centered radical arises from the laser-flash photolysis of the dinuclear complex (Rh(dmgH)/sub 2/PPh/sub 3/)/sub 2/. In the absence of other reagents the radical (which shows an absorption maximum at 580 nm, /epsilon/ = 2 /times/ 10/sup 3/L mol/sup /minus/1/ cm/sup /minus/1/) dimerizes rapidly, with k/sub D/ = 2.3 /times/ 10/sup 8/L mol/sup /minus/1/ s/sup /minus/1/ in 95% ethanol. The metal-centered radical reacts rapidly with O/sub 2/, k = 1.4 /times/ 10/sup 9/ L mol/sup /minus/1/ s/sup /minus/1/, with the first step assigned to the formation of a 1:1 oxygen adduct. This reaction ultimately yields hydrogen peroxide. The reactions between Rh(dmgH)/sub 2/PPh/sub 3/ and a wide range of alkyl halides have also been studied. The rate constants k/sub RX/ span a wide range, from /approx/ 4 /times/ 10/sup 2/ (CHCl/sub 3/) to 9 /times/ 10/sup 8/ (CBr/sub 4/). There is an approximate correlation between log k/sub RX/ and the carbon-halogen bond dissociation energy. A correlation is also found with the half-wave potential for the reaction RX + e/sup /minus// /yields/ R/sup /center dot// + X/sup /minus//. The mechanism of the reactions with alkyl halides is discussed, and it seems probably that these reactions proceed by halogen atom abstraction. 24 references, 5 figures, 2 tables.
Research Organization:
Iowa State Univ., Ames (USA)
DOE Contract Number:
W-7405-ENG-82
OSTI ID:
5852635
Journal Information:
Inorg. Chem.; (United States), Journal Name: Inorg. Chem.; (United States) Vol. 27:18; ISSN INOCA
Country of Publication:
United States
Language:
English