ELECTRON-TRANSFER THROUGH 2,7,9,10-TETRAAZAPHENANTHRENE - A QUANTUM INTERFERENCE EFFECT

Intramolecular electron transfer has been detected in a binuclear comp lex of ruthenium using 2,7,9,10-tetraazaphenanthrene as bridging ligan d. From the characteristics of the intervalence transition, the effect ive coupling V(ab) between ruthenium sites has been determined. It is found to be lower than in the corresponding complex with 4,4'-bipyridi ne, despite the fact that 2,7,9,10-tetraazaphenanthrene presents addit ion connections. Molecular orbital calculations confirm this effect. T he analysis of these differences is performed in terms of ''interferen ce'' effects between the different branches connecting the metal atoms .