Metal complexes of tridentate hybrid ligands. IV. Cobalt complexes of ligands containing the donor sequence As-N-N(heterocyclic)

Abstract

The compounds obtained by the interaction of four new hybrid tridentate ligands, each containing the donor sequence As-N-N, with cobalt(II) salts is described. The four ligands were obtained by the Schiff base condensation of an o-dialkylarsinoaniline and either pyridine-2-aldehyde or 6-methylpyridine-2-aldehyde. Cobalt(II) compounds of the type [Co(ligand) 2]Y 2 (where Y = I, ClO 4 or BPh 4) where obtained for all four ligands, but for the two ligands with blocking 6-methyl-groups upon the pyridine ring, where Y = NO 3, compounds of this type could not be isolated, only mono-compounds of type Co ligand (NO 3) 2 being obtained. Cobalt(II) iodide reacted with all four ligands to yield either a mono- or a bis-ligand complex. On the other hand cobalt(II) chloride, bromide or thiocyanate yielded only 1:1 ligand:cobalt compounds of the two types Co ligand X 2 and [Co(ligand) 2][CoX 4]. Cobalt(II) iodide complexes of this latter type were also obtained in some instances. Physical measurements were undertaken to ellucidate the stereochemistry of the compounds, and in certain cases of anomalous magnetic moments, temperature dependent studies were carried out.