Syntheses and electrochemical properties of ruthenium(II) complexes with 4,4′-bipyrimidine and 4,4′-bipyrimidinium ligands

The syntheses and electrochemical properties of novel ruthenium(II) polypyridyl complexes with 4,4′-bipyrimidine, [Ru(trpy)(bpm)Cl](X) ([1](X; X=PF6−, BF4−)) and with a quaternized 4,4′-bipyrimidinium ligand, [Ru(trpy)(Me2bpm)Cl](BF4)3 ([2](BF4)3) (trpy=2,2′:6′,2″-terpyridine, bpm=4,4′-bipyrimidine, Me2bpm=1,1′-dimethyl-4,4′-bipyrimidinium) are presented. The bpm complex [1]+ was prepared by the reaction of Ru(trpy)Cl3 with 4,4′-bipyrimidine in EtOH/H2O. The structural characterization of [1]+ revealed, that the bpm ligand coordinated to the ruthenium atom with the bidentate fashion. Diquaternization of the non-coordinating nitrogen atoms on bpm of [1]+ by (CH3)3OBF4 in CH3CN gave [2](BF4)3. The electrochemical and spectroelectrochemical properties of the complexes are described.