Thioether-oxime complexes of nickel(II) and copper(II)

Nickel(II) and Copper(II) complexes of tetra- and pentadentate thioether-oxime ligands have been synthesized. An extraordinary range of properties are exhibited by the complexes. The tetradentate thioether-oxime complexes of copper(II) form axial/equatorial dimeric complexes in the solid state. These complexes exhibit weak ferromagnetic coupling between adjacent copper(II) ions. ESR spectra reveal that the dimer is broken in solution, and indeed the ESR spectra reveal tetragonal symmetry about the copper(II) ions in the tetradentate thioether-oximes. The electrochemistry of these complexes supports the fact that oxime-containing ligands stabilize copper(II). Nickel(II) forms a wide range of structures with the tetradentate ligands; the geometries vary from low-spin square planar to high-spin trinuclear complexes. The nickel(II) ions in trimeric complexes are disposed at the corners of an isosceles triangle and couple to each other through weak antiferromagnetic interactions. The electrochemistry of the trimeric nickel(II) complexes reveals that Ni(III) is attainable, due to the presence of anionic donors. Nickel(II) and Copper(II) form octahedral and square-pyramidal complexes with the pentadentate thioether-oxime ligands. The electrochemistry of the Ni(II) complexes reveals that most of the pentadentate ligands can stabilize both Ni(I) and Ni(III).