83602-85-1Relevant academic research and scientific papers
Kinetic and spectroscopic observations on the azidyl, N3{radical dot}, radical oxidation of fac-(Lspectator)ReI(CO)3(Lacceptor ) to fac-(Lspectator)ReII(CO)3(Laccepto r), Lspectator = 4,4′-bpy; Lacceptor ...
Ruiz,Juliarena,Wolcan,Ferraudi
, p. 3681 - 3687 (2007)
Full title: Kinetic and spectroscopic observations on the azidyl, N3{radical dot}, radical oxidation of fac-(Lspectator)ReI(CO)3(Lacceptor ) to fac-(Lspectator)ReII(CO)3(Laccepto r), Lspectator = 4,4′-bpy; Lacceptor = dipyridyl[3,2-a:2′3′-c]phenazine or Lspectator = Cl-; Lacceptor = bathocuproindisulfonate: A revisitation to the self-exchange rate constants of the N3{radical dot} / N3- and Re(II)/Re(I) couples and to the redox potential of the N3{radical dot} radical The oxidation of two triscarbonyl fac-(Lspectator)ReI(CO)3(Lacceptor )z complexes (Lspectator = 4,4′-bpy; Lacceptor = dipyridyl[3,2-a:2′3′-c]phenazine (dppz) and z = + or Lspectator = Cl-; Lacceptor = bathocuproinedisulfonate (bcds2-) and z = 2-) by azidyl radicals, N3{radical dot}, was investigated by pulse radiolysis. Reaction rate constants were determined for the electron transfer reactions between the Re(II) products and reductants, Ru (bipy)33 + and Ni(Me6-[14]dieneN4)2+, and used for the calculation of the self-exchange rate constant of the Re(II)/Re(I) couples. The self-exchange rate constants, k ～ 107 M-1 s-1, were one order of magnitude larger than the constant, k ～ 106 M-1 s-1, communicated in the literature for the [Re(DMPE)3]+/2+ (DMPE = 1,2-bis(dimethylphosphine)ethane). The larger rate constants of the triscarbonyl complexes are in agreement with the smaller inner sphere reorganization energy of the complexes relative to [Re(DMPE)3]+/2+. Moreover, the study demonstrated that the redox potential of the azidyl radicals is EN3{radical dot} / N3-0 = 1.70 V versus NHE, a value larger than one communicated earlier, and that the self-exchange rate constant of the N3{radical dot} / N3- couple is kN3{radical dot} / N3- = 2.7 × 106 M- 1 s- 1. The small value of the N3{radical dot} / N3- self-exchange rate constant has been related to the large solvent reorganization energy of the reaction.
