Acid-Base and Electrochemical Properties of the MLCT Excited States and One-Electron-Reduced Forms of Ruthenium(II) Complexes Containing 2-(2'-Pyridyl)pyrimidine and 2,2'-Bipyridine in Aqueous Solution

Abstract

The acid-base and electrochemical properties of the MLCT excited states and the one-electron-reduced forms of the three Ru(bpy)(3)(-)()(p)()(pypm)(p)()(2+) complexes, where bpy = 2,2'-bipyridine, pypm = 2-(2'-pyridyl)pyrimidine, and p = 1-3, have been examined in aqueous solution; a determination has been made of the ground- and excited-state electrochemical potentials, the values of the pK(a) and deprotonation rate constants of the conjugate acids of the excited states and the one-electron-reduced complexes, and the kinetics of the second-order decays of the reduced species. Comparison is made with the behavior of the analogous 10 complexes of the form Ru(bpy)(3)(-)()(m)()(-)()(z)()(bpm)(m)()(bpz)(z)()(2+), where bpm = 2,2'-bipyrimidine, bpz = 2,2'-bipyrazine, m and z = 0-3, and m + z </= 3, which have been studied in detail before.