Structural variations in polynuclear copper(II) complexes based on salicylaldimine type ligands along with dicyanamido co-ligand
摘要:
Two new polynuclear complexes of Cu(II), [(CuL1)Cu(N3C2)(2)](n) (1) and [(CuL2)(2)Cu(N3C2)(2)]center dot H2O (2), have been synthesized by reacting the "ligand complexes", [CuL1] and [CuL2] respectively with copper perchlorate and sodium dicyanamide (NaN3C2) in ethanol-water, where the di-Schiff base ligands H2L1 = N,N'-bis(salicylidene)-1,3-propanediamine and H2L2 = N,N'-bis(alpha-methylsalicylidene)-1,3-propanediamine. Structural analysis shows that complex 1 is a 2D polymer formed by linking the dinuclear units through a mu(1,5)-dicyanamido bridge. It contains alternating helical chains of P and M types. Complex 2 is a discrete bent trinuclear species where phenoxido groups of two terminal "ligand complexes" coordinate to a central Cu(II) along with terminally coordinated dicyanamido anions. Both complexes exhibit irreversible reductive Cu(II)/Cu(I) and quasi-reversible oxidative Cu(II)/Cu(III) responses in cyclic voltammetry. The electrochemically generated Cu(I) species for both complexes are unstable and undergo disproportionation to Cu-o and Cu2+. (C) 2012 Elsevier Ltd. All rights reserved.