The first triple phenoxido-bridged triangular Ni^IICu^II₂ complexes with a N₂O₂ donor di-Schiff base and pseudohalide (N(CN)₂⁻ or NCS⁻) ligands: Structural analyses and magnetic properties

Abstract

Two triangular tri-nuclear, hetero-metallic copper (II)-nickel (II) complexes, [(CuL)₂Ni{N(CN) ₂}₂]•H₂O (1) and [(CuL) ₂Ni(NCS) ₂]•H₂O (2) have been synthesized by reacting “ligand complex” [CuL] with Ni(ClO₄)₂ in presence of polyatomic anions, dicyanamide (dca) or thiocyanate in methanol–water medium, where H₂L is a N₂O₂ donor di-Schiff base derived from 1,3-propanediamine and 2-hydroxyacetophenone. Both the complexes have been structurally and magnetically characterized. In both complexes, two [CuL] units coordinate to a nickel atom through the coordination of the phenoxido oxygen atoms forming triple phenoxido bridges between each Cu (II) and Ni (II). A couple of terminal dca or N-bonded thiocyanate ions complete the distorted octahedral geometry around Ni (II) in 1 and 2 respectively. Variable temperature magnetic susceptibility measurements show the presence of moderate antiferromagnetic exchange interactions mediated through the phenoxido bridges with J values (H = −JΣS_iS_i+1) of −49 and −42 cm⁻¹ for 1 and 2 respectively.