Preparation and study of pyridothienopyrazines and their Ruthenium(II) complexes: a new family of bidentate ligands

The Friedlander condensation of 3-aminothieno[2,3-b]pyrazine-2-carboxaldehyde with either methyl ketones or carbocyclic and heterocyclic ketones leads to a family of new bidentate ligands containing a pyridothienopyrazine coordinating unit. Complexation with [Ru(bpy)2Cl2] affords the corresponding six-coordinated Ru(II) complexes. The structures were analyzed by 1H NMR spectroscopy, which shows shielding effects reflecting significant interligand π-stacking interaction in the complexes. The photophysical properties of the ligands and their metallic complexes have been also examined.