Electrochemical and spectroelectrochemical studies of (i) actinide double-decker porphyrins and phthalocyanines, (ii) monomeric europium(III) porphyrins, (iii) tin(II) binuclear porphyrins, and (iv) buckminsterfullerene

The redox properties of metalloporphyrins, metallophthalocyanines and Buckminsterfullerene, C60, were investigated by electrochemistry and/or spectroelectrochemistry in non-aqueous media. The investigated macrocyclic compounds include double-decker metalloporphyrins and metallophthalocyanines containing actinide metal ions, monomeric europium porphyrins and metal-metal bonded Sn(II) porphyrins. The homoleptic and hereoleptic actinide double-decker complexes are represented as M(P)2, M(Pc)2, M(P)(P') and M(P)(Pc), where M is U or Th, P and P' are the dianions of two different porphyrins and Pc is the phthalocyanine dianion. These compounds undergo up to three reversible one-electron oxidations and up to four reversible one-electron reductions in non-aqueous media. Spectroscopic and electrochemical criteria demonstrated the existence of mixed or separate sets of orbitals depending upon the nature of the two macrocycles and the specific oxidation state of the sandwich species. This is discussed in this dissertation in terms of ring/ring interactions, porphyrin substituent effects and data in literature on other double-decker complexes. Monomeric europium tetraphenylporphyrins containing a β-diketonate axial ligand can be stepwise oxidized in two one-electron abstractions or stepwise reduced in four half-an-electron additions. The data is consistent with dimerization in solution upon electroreduction. Sn(II) five-coordinate porphyrins containing a carbenoid Sn-Fe bond and a single hydrophobic chain attached to one of the four phenyl groups of the macrocycle are also reduced via two one-electron additions to the π-ring system. They can also be electrooxidized. Finally, the effect of solvent molecular features on the thermodynamics and kinetics of the sequential one-electron electroreduction of C60 was investigated in aprotic solvents of different polarity, polarizability and viscosity