Syntheses of a unique molecule, nickel(ii) dithiocarbamate bearing two ferrocenyl groups (3), and its oxidized product, nickel(iv) dithiocarbamate bearing three ferrocenyl groups (4 ), are reported. Spectroelectrochemical investigations have shown that the complex 4 undergoes a three-electron oxidation process, according to two quasireversible steps
2 ) and results from the combination of a statistical contribution and a term which reflects the electrostatic repulsive interaction between the metal centers. In spite of the chemical equivalence of the three ferrocenyl groups, the mixed-valence state [Ni IV -Fe III (Fe II ) 2 ] 2 (4 2 ) substantially persists in solution. Model studies with ethylenebridged bis(ferrocenylimine) ( 6) have revealed that the electrostatic term is much lower in the absence of the nickel(iv) center. Preliminary force-field simulations on 4 have shown that enhanced electrostatic repulsion caused by the oxidation of the ferrocenyl subunits affects the conformation of the molecule, which results in a significant dimensional increment. Stereochemical features of the molecules are related to the electrostatic interaction and DG 0 associated with the comproportionation process is affected by such strong deformation that a decrease in electrostatic repulsion results.