Homoleptic and heteroleptic iron(II) and ruthenium(II) complexes of novel 4′-nitro-2,2′:6′,2"-terpyridines and 4′-amino-2,2′:6′,2"-terpyridines

Several series of 4-nitro-6-bromo-2,2'-bipyridines and of symmetrical and unsymmetrical 4'-nitro- and 4'-amino-2,2' : 6',2 "-terpyridines have been prepared. The structure of 4'-amino-2,2' : 6',2 "-terpyridine has been determined by X-ray structure analysis. The unusual internal angles of the two terminal rings with respect to the central one have been rationalized in terms of hydrogen bonding between the amino protons and nitrogen atoms of the terminal pyridine rings. The new ligands have been used in the preparation of homo- and heteroleptic ruthenium(II) and iron(II) complexes and their chemical and electrochemical properties have been investigated. The synthesis and properties of a heteroleptic iron(II) complex with both 4'-nitro- and 4'-amino-2,2' : 6',2 "-terpyridines are reported for the first time.