Preparation and properties of new Di-N-alkylated 14-membered tetraaza macrocycles and their nickel(II) and copper(II) complexes

Abstract

New 14-membered tetraaza macrocycles 1,8-diallyl-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane (L-2) and 1,8-bis(n-propyl)-3,5,7,7,10,12,14,14-octamethyl-1,4,8,1.1-tetraazacyclotctradecane (L-3) have been prepared by direct reaction of 2,5,5,7,9,12,12,14-octamethyl-1,4,8,11-tetraazacyclotetradecane (L-1) with allyl bromide or n-propyl bromide. The nickel(II) and copper(II) complexes of L-2 and L-3 have been prepared. The macrocycles show high copper(II) selectivity against nickel(II) ion in methanol solutions containing water. The wavelengths (ca. 505 nm) of the d-d bands for the nickel(II) complexes are extraordinarily longer than those for the complexes of L-1 and other related di N-alkylated 14-membered tetraaza macrocycles. Crystal structure of [NiL2](ClO4)(2) shows that the average Ni-N bond distance (1.992 Angstrom) of the complex is distinctly longer than those of other related nickel(II) complexes. Effects of the N- and C-substituents on the properties of the macrocyclic compounds are discussed.