SYNTHESIS, ELECTROCHEMISTRY AND PHOTOEXCITED-STATE PROPERTIES OF DINUCLEAR RUTHENIUM COMPLEXES BRIDGED BY 2,6'-BIS(2-PYRIDYL)-2,2' 6,2''-THIAZOLO[4,5-D]-BENZOTHIAZOLE/

The new bridging ligand, 2,6'-bis(2-pyridyl)-2,2': 6,2''-thiazolo[4,5- d]-benzothiazole (bptb) and its dinuclear Ru complexes have been synth esized. The combination of the transient absorption (TA) spectra and s pectroelectrochemical difference spectra has led to the assignment of the lowest excited state for the dinuclear Ru(II) complexes as a Ru-to -bptb charge transfer state. Although the ab initio molecular calculat ions of bridging ligands have provided lower HOMO/LUMO energies for bp tb compared to those of 2,6-bis(2-pyridyl)benzodiimidazole (dpimbH(2)) , the degree of electronic coupling for the dinuclear bptb complex is smaller than that for the dpimbH(2) complex from the analysis of inter valence charge transfer band. Since both dinuclear Ru complexes have a similar coordination environment, the Ru d pi-HOMO L pi mixing is dom inant for the metal-metal interaction through the hole transfer mechan ism.