Structural development of free or coordinated 4′-(4-pyridyl)-2,2′:6′,2"-terpyridine ligands through N-alkylation:: New strategies for metallamacrocycle formation

A series of N-alkylated derivatives of [Ru(pytpy)(2)](2+) (pytpy = 4'-(4-pyridyl)-2,2':6',2"-terpyridine) has been synthesised and characterised. These include both model and functionalised complexes that complement previously reported iron(II) analogues. Reaction of [Ru(pytpy)(2)](2+) with bis[4-(bromomethyl)phenyl]methane leads to the formation of a [2+2] ruthenamacrocycle. Related ferramacrocycles could not be accessed by this route, and instead were prepared in two steps by first reacting bis[4-(bromomethyl)phenyl]methane or 4,4'-bis(bromomethyl)biphenyl with two equivalents of pytpy, and then treating the resulting bis(N-alkylated) product with iron(II) salts.