.- Kinetic and spectroscopic observations on the azidyl, N3•, radical oxidation of fac-(Lspectator)ReI(CO)3(Lacceptor) to fac-(Lspectator)ReII(CO)3(Lacceptor), Lspectator = 4,4'-bpy; Lacceptor = dipyridyl[3,2-a:2’3’-c]phenazine or Lspectator = Cl-; Laccep

G. T. RUIZ; M. P. JULIARENA; E. WOLCAN; G. FERRAUDI

INORGANICA CHIMICA ACTA

Elsevier

Lugar: Amsterdam; Año: 2007 vol. 360 p. 3681 - 3687

0020-1693

The oxidation of two triscarbonyl fac-(Lspectator)ReI(CO)3(Lacceptor)z complexes (Lspectator = 4,40-bpy; Lacceptor = dipyridyl[3,2-a:2030-c]phenazine (dppz) and z = + or Lspectator = Cl; Lacceptor = bathocuproinedisulfonate (bcds2) and z = 2-) by azidyl radicals, N3, wasinvestigated by pulse radiolysis. Reaction rate constants were determined for the electron transfer reactions between the Re(II) productsand reductants, RuðbipyÞ33þ 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 M1 s1, were one order of magnitude larger than the constant,k  106 M1 s1, communicated in the literature for the [Re(DMPE)3]+/2+ (DMPE = 1,2-bis(dimethylphosphine)ethane). The larger rateconstants 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 E0N3=N3 ¼ 1:70 V versus NHE, avalue larger than one communicated earlier, and that the self-exchange rate constant of the N3=N3 couple is kN3=N3 ¼ 2:7  106 M1 s1. The small value of the N3=N3self-exchange rate constant has been related to the large solvent reorganizationenergy of the reaction.