Synthesis, Characterization and Coordination Chemistry of the New Tetraazamacrocycle 4,10-dimethyl-1,4.7,10-Tetraazacyclododecane-1,7-bis(methanephosphonic acid monoethyl ester) dipotassium salt

A new potentially hexadentate tetraazamacrocycle based on the cyclen skeleton has been synthesized and fully characterized. The macrocycle 4,10-dimethyl-1,4,7,10-tetraazacyclododecane-1,7-bis(methanephosphonic acid monoethyl ester) dipotassium salt (Me2DO2PME) contains mutually trans monoethyl ester phosphonate acid substituents on two nitrogen atoms, and trans methyl substituents on the other two nitrogen atoms.Structural information on the neutral complex [Cu(Me2DO2PME)] has been obtained by a solution X-Band EPR study. The redox chemistry of [Cu(Me2DO2PME)] in dimethyl solfoxide and water has been studied by electrochemical measurements. Cyclic voltammetry in DMSO shows the complex to undergo a quasireversible one-electron reduction step leading to an unstable CuI species.