Transmission of electronic effects in some substituted phenyl derivatives of cobalt(III) bis(acetylacetone)ethylenedi-imine complexes
The 1H n.m.r. spectra of a series of para-substituted phenyl derivatives of bae-cobalt complexes ([H2bae = bis(acetylacetone)ethylenedi-imine] have been measured. The chemical shifts of all the hydrogens in the planar ligand are dependent on the axial ligand. It is concluded that through-space effects are mainly responsible for the dependence on the axial ligand of the difference in the chemical shifts of the A2 and B2 hydrogens of the ethylene-di-imine bridge system whilst changes in electron density transmitted by way of the bonding electrons are mainly responsible for the variations in the chemical shifts of the methene and methyl hydrogens which are related to the Hammett σ-para-functions of the para-substituent in the axial ligand. A similar correlation is observed with the formation constants of the six-co-ordinate pyridine and piperidine complexes.