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

Abstract

One linear homo-metallic trinuclear [{CuL¹(CH₃OH)} ₂ Cu(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(CH₃ OH)}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.