Kinetic and Thermodynamic Control in Self-Assembly: Sequential Formation of Linear and Circular Helicates

NMR and MS analysis as a function of time has shown that the self-assembly of a linear ligand with Fe²⁺ or Ni²⁺, metal ions of octahedral coordination geometry, generates first a triple helicate and thereafter the circular helicate 1 as kinetic and thermodynamic products, respectively. The results provide insight into features of the energy hypersurface on which this self-assembly operates and point to the general role of kinetic and thermodynamic control in such processes.