Use of Cu(II)-di-Schiff bases as metalloligands in the formation of complexes with Cu(II), Ni(II) and Zn(II) perchlorate

One linear homo-metallic trinuclear [{CuL1(CH3OH)}2Cu(ClO4)2] (1); five trinuclear hetero-metallic; bent [(CuL1)2Ni(H2O)2](ClO4)2·H2O (2), linear [(CuL1)2Zn(ClO4)2] (3), bent [{CuL2(ClO4)}{CuL2(CH3OH)}Ni(CH3OH)2](ClO4)·(CH3OH)·0.25(H2O) (4), triangular [(CuL2){CuL2(CH3CN)}Ni(CH3CN)2](ClO4)2 (5), triangular [(CuL2)2Ni(H2O)2](ClO4)2·3H2O (6) and one rare tetranuclear star-shaped [{CuL2(H2O)}2(CuL2)Zn](ClO4)2·H2O (7) complexes have been synthesized by reacting the “metalloligand”, [CuL1] or [CuL2] with corresponding metal perchlorate where the di-Schiff base ligands H2L1 = N,N′-bis(salicylidene)-1,3-propanediamine and H2L2 = (N,N′-bis(α-methylsalicylidene)-1,3-propanediamine. The structures of all the seven complexes have been determined by X-ray crystallography. Structural analysis shows that complexes 1–6 are discrete trinuclear species where phenoxido groups of two terminal “metalloligands” coordinate to a central Cu(II) in 1 or Ni(II) in 2, 4–6 or Zn(II) in 3. In 1 and 3 two trans axial positions of the central Cu(II) are weakly coordinated by the oxygen atoms of perchlorate anions and the molecules are linear. However, in 2, 4–6 two solvent molecules coordinate to the cis positions of the central Ni(II) to complete its distorted octahedral geometry that makes the molecules bent or triangular. On the other hand, complex 7 is a star-shaped tetranuclear species. In which three metalloligands bind a central Zn(II) ion through double phenoxido bridge.

Graphical abstractFormation of two linear (Cu3 and ZnCu2), two bent (NiCu2), two triangular (NiCu2) and one novel star-shaped ZnCu3 complexes by the reaction of perchlorate salts of metal ions (e.g. Ni(II), Cu(II) and Zn(II)) with Cu(II)-di-Schiff bases as metalloligands show that neuclearity and shape of complexes depend upon the central metal ion, metalloligands as well as coordination solvents.Figure optionsDownload full-size imageDownload as PowerPoint slide