Metal complexes of tridentate hybrid ligands. III. Cobalt and nickel complexes of ligands containing the donor sequence As-N-N

Abstract

The compounds obtained from the interaction of four new hybrid tridentate ligands, each containing the donor atom sequence N-N-As, with cobalt(II) and nickel(II) salts is described. The four ligands, obtained by the Schiff's base condensation of o-dimethyl- or o-diethyl-arsinoaniline and a suitable aldehyde, possess a terminal nitrogen donor present in (i) an NMe 2 group, (ii) an NHMe 2 group, or (iii) a pyrrole ring. With ligands of the first two types, compounds of formula [MligandX 2] (where X = halogen, NCS or NO 3; M = Co or Ni) can be prepared. In the cases where X = halogen, five-coordination is proposed, while the thiocyanate and nitrate compounds may be five-coordinate or octahedral depending upon the ligand and the metal present. Complexes derived from the ligand of type (iii) may posses either protonated or deprotonated ligand residues, and a number of different types of nickel(II) and cobalt(III) compounds were isolated.