Binuclear copper(II) complexes of new bis(macrocyclic) 16-membered pentaaza subunits are linked together by bridging nitrogen of amine: Synthesis, characterization and catalytic activity

Abstract

New bis(macrocyclic) dicopper(II) complexes containing phenylene bridges between 16-membered pentaaza macrocyclic subunits have been synthesized via one-pot template condensation of nitrogen–nitrogen linker (1,4-phenylenediamine; benzidine; 4,4′-diaminodiphenylmethan; 4,4′-diaminodiphenylether; 4,4′-diaminodiphenylsulfon), formaldehyde, 1,3-diaminopropane, copper(II) and 2,4-pentanedione in a 1:4:4:2:2 molar ratio results in the formation of new series of binuclear copper(II) complexes; “dichloro[1-phenyl- ( 1); 1,1′-phenyl- ( 2); 1,1′-diphenylmethan- ( 3); 1,1′-diphenylether- ( 4); 1,1′-diphenylsulfon- ( 5)] bis(8,10-dimethyl-1,3,7,11,15-pentaazacyclohexadeca-7,11-diene)copper(II), {[Cu(Me 2[16]aneN 5)] 2RCl 4}”. {[Cu(Me 2[16]aneN 5)] 2R}(ClO 4) 4 ( 6– 10) was prepared by a method similar to that for {[Cu(Me 2[16]aneN 5)] 2RCl 4} ( 1– 5) except that copper(II) perchlorate was used instead of copper(II) chloride. Elemental analyses, IR, UV–vis spectroscopy, conductometric and magnetic measurements have been used to characterize the new bis(macrocyclic) binuclear copper(II) complexes. The spectra of {[Cu(Me 2[16]aneN 5)] 2R} +4 shows that the four nitrogen atoms are coordinated to the copper(II) ion. These bis(macrocyclic) complexes catalyzed efficiently the selective oxidation of tetrahydrofuran into tetrahydrofuran-2-one and a small amount of tetrahydrofuran-2-ol and 4-hydroxybutyraldehyde using diluted H 2O 2 as the oxidant. The influence of solvent, time and concentration of catalyst has been studied. 1,1′-Diphenylsulfonbis(8,10-dimethyl-1,3,7,11,15-pentaazacyclohexadeca-7,11-diene)copper(II) perchlorate ( 10) shows significantly higher catalytic activity vthan other bis(macrocycle) binuclear copper(II) complexes.