Some Studies in Inorganic Complexes. VIII. Cobalt(II) and Cobalt(III) with 2-Picolylamine

Abstract

Complexes of cobalt(II) and (III) with the chelating ligand 2-picolylamine have been prepared and studied. Those of cobalt(II) are Copic₃(ClO₄)₂ and CopicI₂.2H₂O, where pic is the ligand 2-picolylamine. Measurements of magnetic susceptibility have shown that in both of these the cobalt atom is spin-free, giving rise to momenta of 4.8 and 4.9B.M. respectively. By means of conductance measurements in water, methanol, nitromethane, and nitrobenzene, it has been shown that the former is an octahedral complex and the latter, whilst probably octahedral, could be tetrahedral. The cobalt(III) complexes described include [Copic₃](ClO₄)₃, [Copic₂Cl₂]Cl.HCl, [Copic₂Cl₂]Cl, [Copic₂₍NO₂)₂]NO₃.½H₂O, [Copic₂(NO₂)₂]NO₂, and [Copic₂(H₂O)₂](ClO₄)₂. By means of the above measurements it has been shown that all the latter are diamagnetic octahedral complexes. A study of absorption spectra in the visible region, in the above solvents where possible, has also been made and the results correlated to solution stability. Attempts to resolve the Copic₃³⁺ complex into its enantiomorphs were unsuccessful.