Synthesis and structural characterization of copper complexes of N_4 tetradentate Schiff bases derived from N-alkylated 2-aminobenzaldehyde.Effects of cyclization,oxidation,and dinucleation

摘要

The structures of the copper complexes of 7,8,15,16,17,18-hexahydro-dibenzo[e.m][1,4,8,11]tetraazacyclotetradecine (Cu(2,2 mac))7,8,15,18-tetrahydro-dibenzo[e,m][1,4,8,11]tetraazacyclotetradecine-16,17-dionato (Cu(2,2 oxomac)) and Cu(N-CH_3 amben) and Cu(2,2 oxomac)Ni(hfa)_2 are reported.The three copper complexes containing a 14-membered macrocycle are essentially square planar complexes and exhibit no short axial interactions.The analogous acyclic complex,Cu(N-CH_3 amben),exhibits an average tetrahedral distortion of 34.35 deg which appears to be due to steric repulsion between the two methyl groups.The dinuclear complex,which exhibits a planar exchange coupled oxamido core,was prepared by reaction of Cu(2,2 oxomac) with Ni(hfa)_2.The analogous complex,Cu(2,2 oxomac)Cu(hfa)_2.can be prepared by the same procedure or by reaction of Cu(2,2 mac) with Cu(hfa)_2.The former method is a general synthetic route while the latter is specific for Cu(hfa)_2 relying on its ability to catalyze the oxidization of the ethylene unit between the anilino nitrogen atoms to the oxamide (N-CH_2-CH_2-N- to N-CO-CO-N-)under ambient conditions.