Metal complexes of tridentate hybrid ligands. II. Cobalt and nickel complexes of ligands containing the donor sequence AsNS

Abstract

Some nickel(II) and cobalt(II) complexes of six new hybrid tridentate ligands, all possessing the potential donor atom sequence of AsNS, have been synthesised and studied. The ligands are of two types and were prepared by the condensation of o-dialkylarsinoanilines with (i) o-methylthiobenzaldehyde. (ii)2-thiophenaldehydes. With type (i) ligands, complexes of formula [M ligand X 2] (where M = Co or Ni, X = anionic group) and [M(ligand) 2]Y (where M = Co or Ni, Y = ClO 4 or BPh 4) were obtained. In [Co ligand X 2] (where X = Br, I or NO 3) the ligand appears to act as a bidentate NAs ligand only. However, the [M(ligand) 2] 2+ cations appear to possess octahedral stereochemistry. The [Ni ligand X 2] compounds are five-coordinate where X = Cl, Br or I, but octahedral where X = NCS. Ligands of type (ii) acts as bidentate NAs ligands to give Ni(ligand) 2X 2 compounds. The nature of X determines whether such complexes are of high or low-spin tetragonal stereochemistry.