N,N'-Bis(3-methoxysalicylidene)propane-1,2-diamine mononuclear 4f and heterodinuclear Cu-4f complexes: Synthesis, crystal structure and electrochemical properties

摘要

Reactions of H_2L [H_2L=N,N'-bis(3-methoxysalicylidene)propane-1,2-diamine] and Ln(NO_3)_3 _ 6H_2O give rise to two different mononuclear 4f complexes, namely, ([(H_2L)La(NO_3)_3(MeOH)] _ H_2O}_n (1) and [(H_2L)Nd(NO_3)_3] (2). Further additions of Cu(Ac)_2_ H_2O to the mononuclear 4f complexes yield expected heterodinuclear Cu-4f complexes [LCu(Me_2CO)Ln(NO_3)_3] (3, Ln = Nd; 4, Ln = Eu; 5, Ln = Dy). Complex 1 is a unique 1D polymeric chain structure, and 2 is one of the few structurally characterized discrete hexadentate salen-type mononuclear 4f complexes. Complexes 3-5 are similar to their analogues. However, they are prepared by a reversed synthetic route in contrast to their isomorphic complexes. Electrochemical behavior of heterodinuclear Cu-4f complexes 3-5 has been examined by cyclic voltammetry in acetonitrile. The redox potential of heterodinuclear Cu-4f complexes 3-5 shows significant anodic shift comparing to that of mononuclear copper complex (LCu). A tendency of anodic shift was observed in a sequence of 3＜4＜5. This results from the modulating effect of coordination geometry around Cu(ll) ion on redox potential.