Organic substituent effects in macrobicyclic (hexaamine)cobalt(III/II) complexes: a new method of obtaining polar substituent constants

The redox potentials, E 1/2 , for the reversible cobalt (III/II) redox couples of complexes of substituted macrobicyclic ligands derived from 3,6,10,13,16,19-hexaazabicyclo[6.6.6]icosane show a substantial variation with the type of substituent. The variation was subjected to a Hammett type treatment yielding a series of inductive or polar substituent constants σ E that correlate with the organic substituent constants obtained by a variety of other methods