Synthesis and Characterization of New Tetraaza Macrocycles Bearing Two or Four N-Methoxyethyl Pendant Arms and Their Copper(II) and/or Nickel(II) Complexes

This work shows that both L² and L³ bearing two and four N-(CH₂)₂OCH₃ groups, respectively, can be prepared selectively by the reaction of L¹ with 1-bromo-2-methoxyethane. The di-N-substituted macrocycle L² readily forms its copper(II) and nickel(II) complexes. The N-(CH₂)₂OCH₃ groups in [CuL²]²⁺ are coordinated to the metal ion, whereas those in [NiL²]²⁺ are not involved in coordination. Interestingly, L³ reacts with CU²⁺ ion to form [Cu(HL³)]³⁺, in which one tertiary amino group is not involved in coordination. A variety of work has been concerned with the preparation of polyaza macrocyclic ligands and complexes bearing additional functional pendant arms because of their interesting chemical properties and potential applications. In general, coordination geometry and chemical properties of such compounds are strongly influenced by the nature and number of the functional groups. Some polyaza macrocyclic complexes bearing pendant ether group(s), such as [CuL⁴]²⁺, [NiL⁵]²⁺, and [NiL¹⁰]²⁺, have been prepared and investigated. The preparation of [CuL⁴]²⁺ and [NiL⁵]²⁺ bearing two and one N-CH₂OCH₃ groups, respectively, has been achieved by the reaction of L¹¹ with methanol in the presence of the corresponding metal ion