41673-52-3Relevant 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 (2008/10/09)
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.
Ground- and excited-state electron-transfer reactions: Photoinduced redox reactions of poly(pyridine)ruthenium(II) complexes and cobalt(III) cage compounds
Mok, Chup-Yew,Zanella, Andrew W.,Creutz, Carol,Sutin, Norman
, p. 2891 - 2897 (2008/10/08)
Rate constants for the quenching of poly(pyridine)ruthenium(II) (RuL32+) excited states by caged cobalt(III) amine complexes (Co(cage)3+) range from 2 × 108 to 1 × 109 M-1 s-1 at 25°C. The quenching process involves parallel energy transfer (ken ～ 1 × 108 M-1 s-1) and electron transfer (kel = (0.1-1) × 109 M-1 s-1) from *RuL32+ to Co(cage)3+. The rate constants for electron-transfer quenching are consistent with expectations based on an adiabatic semiclassical model. The yields of electron-transfer products range from 0.3 to 1.0, increasing as the rate constants for the back-reaction of RuL33+ with Co(cage)2+ diminish. The relatively low magnitudes of the back-reaction rate constants, (0.08-8) × 108 M-1 s-1, are consistent with the high yields of electron-transfer products and derive from poor coupling of the RuL33+ and Co(cage)2+ orbitals.
