Cu(I) and Cu(II) dinuclear complexes of a New Hexaaza Schiff base dinucleating macrocyclic ligand and their oxygenation chemistry

Abstract A new macrocyclic hexaaza binucleating Schiff base ligand 3,7,11,19,23,27-hexaazatricyclo[27.3.1.1 13,17 ]tetratriaconta-1(32),2,11,13(14),15,17(34),18,27,29(33),30-decaene (MX 2 DIPN 2 or 1 ) has been prepared in good yield by direct condensation of m -phthalaldehyde and 3,3′-iminobis(propylamine). MX 2 DIPN 2 forms a dinuclear Cu(I) complex that reacts with molecular oxygen to form [(MX 2 DIPN 2 )Cu 2 (O 2 )] 2+ . This oxygen complex does not undergo intramolecular oxygen insertion into the phenyl ring in sharp contrast with its macrocyclic analog [(MX 2 DIEN 2 )Cu 2 (O 2 )] 2+ (MX 2 DIEN 2 is the macrocyclic ligand formed by the condensation of m -phthalaldehyde and diethylenetriamine), the result of the enlargement of the macrocyclic cavity. It has been shown that [(MX 2 DIPN 2 )Cu 2 (O 2 )] 2+ is an efficient and selective catalyst for the oxidation of 3,5-di- t -butylcatechol to 3,5-di- t -butyl-1,2-benzoquinone in the presence of 1 atm O 2 . Furthermore, the measured initial rate constants reveal that it reacts much faster than any of the related macrocyclic systems reported to date.