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

The acid-base and electrochemical properties of the MLCT excited state s 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)pyr imidine, and p = 1-3, have been examined in aqueous solution; a determ ination 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-redu ced complexes, and the kinetics of the second-order decays of the redu ced 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 les s than or equal to 3, which have been studied in detail before.