Control of the redox activity of anthraquinone through an appended nickel(II)-cyclam side chain. A two-site three-electron redox system
摘要:
The conjugate system 1 has been prepared through reaction of 2-chloromethylanthraquinone with a five-fold excess of cyclam in chloroform at room temperature. Reaction of 1 with NiX2.6H2O (X = Cl, ClO4) gave the corresponding Ni(1)X2 complexes, in which the metal centre has been incorporated by the tetraaza-macrocyclic subunit. The redox behaviour of the nickel(II) complexes has been investigated in a CH2Cl2 solution of 0.1 M Bu4NX, by voltammetric techniques. Two-phase reduction of the quinone subunit of the Ni(1)X2 complex in CH2Cl2 by aqueous Cr(II) takes place at a rate much higher than that observed for the simple anthraquinone molecule, but the reduced conjugate system partitions between CH2Cl2 and water.