Abstract
Ru(bpy)2L2+ (L = bipyrimidine, bipyrazine; bpy = 2,2'-bipyridine) reacted with OR3+ (R = Me, Et) to give Ru(bpy)2L14+ (L1 = N',N'-dialkyl L derivs.). Cyclic voltammetry of Ru(bpy)2L14+ indicated 2 reversible redn. steps and 1 irreversible oxidn. step for the bipyrimidine deriv. and 1 reversible redn. step and 1 irreversible redn. and oxidn. step for the bipyrazine complex. Ru(bpy)2L14+ were characterized by electronic absorption and ESR spectra. Incorporation into a common p system results in strong electronic coupling between the 4,4'-bipyridinium and the tris(a-diimine) chelate functions with significantly altered spectroscopic properties. The isomeric complexes with 4,4'-diquaternized 2,2'-bipyrazine ligands exhibit smaller electronic coupling and irreversible second redn. to a non-Kekule system which helps to understand the superior photosensitizing properties of 2,2'-bipyrazine complexes. on SciFinder(R)
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