Copper(II) and Nickel(II) Complexes of Pentaaza Macrocyclic Ligands

Abstract

The preparations of the pentaazamacrocyclic ligands 1,4,7,10,13-pentaazacyclopentadecane, cpad , l,4,7,l0,13-pentaazacyclohexadecane, ched , l,4,7,l0,14-pentaazacycloheptadecane, chad , 1,4,7,11,14-pentaazacycloheptadecane, cnad , 1,4,7,11,15-pentaazacyclooctadecane, cnad , 1,4,8,11,15-pentaazacyclooctadecane, cnad , 1,4,8,12,16-pentaazacyclononadecane, cnad , and 1,5,9,13,17-pentaazacycloeicosane, ceic , as well as the new linear pentaamine N-(3-aminopropy1)- N'-[3-[(3-aminopropyl)amino] propyl ]propane-1,3-diamine, tpah , are described. Copper(II) and nickel(II) complexes of the above ligands have been prepared and characterized. The nickel(II) complexes of the smaller macrocycles and the linear pentaamine contain Ni^II in a tetragonally distorted octahedral environment in the presence of coordinating anions or in aqueous solution but the [Ni( cnad )]²⁺ and [Ni( ceic )]²⁺ cations are five-coordinate both in the solid state and in aqueous solution. The copper(II) complexes of the macrocyclic pentaamines appear to be square-pyramidal on the basis of their electronic spectra, whereas the complex [cu( tpah )]²⁺ is probably trigonal- bipyramidal.