Pressure studies on the intramolecular isomerization reactions of (Diethylenetriamine)(methyldiethylenetriamine)cobalt(III) and Bis(diethylenetriamine)cobalt(III) cations

Abstract

The homogeneous intramolecular isomerization reactions of all the isomers of [Co(dien)₂] (ClO₄)₃ and [Co(dien)(medien)] (ClO₄)₃ (dien, diethylenetriamine; medien, 4-methyldiethylenetriamine) have been studied at 90°C under atmospheric pressure and conditions of high pressure. The isomerization reactions are retarded by an increase in pressure, and for a given starting isomer of each system: the various isomerization processes are affected uniformly. For each system, the same equilibrium isomer distribution was obtained regardless of starting isomer or of the pressure conditions of the experiment. The results are interpreted on the basis of a common mechanism for all isomerizations, involving Co-N bond-rupture followed by rearrangement of the resultant five-coordinate species.