Phenanthroline-appended porphyrazines: synthesis and conversion into solitaire Ru(II) complexes

Unsymmetrical porphyrazines (tetraazaporphyrins) bearing a single bidentate phenanthroline chelating group M[pz(t-butylphenyl)6phen] have been prepared by the base-catalyzed cross condensation of 3,4-bis(4-tert-butylphenyl)pyrroline-2,5-diimine (in excess) with 6,7-dicyanodipyridoquinoxaline. Treatment of these centrally metalated (M=Mg, Zn) ligands with various Ru(II) salts has yielded several bimetallic complexes including the first coordinatively linked porphyrazine trimer. The optical properties of these complexes are shown to be a function of the additional ligands surrounding the asymmetric ruthenium center.