Electrochemistry and spectroelectrochemistry of zirconium(IV) and hafnium(IV) phthalocyanines with β-diketone axial ligands in nonaqueous media

Abstract

Fourteen ZrIV and HfIV phthalocyanines containing different β-diketone axial liangds were characterized in CH2Cl2 containing 0.1 M TBAP as to their electrochemical and spectroelectrochemical properties. No significant difference in electrochemical behavior was seen between the ZrIV and HfIV complexes. These compounds exhibit up to three oxidations and four reductions under the given solution conditions and the HOMO-LUMO gap ranges from 1.56 to 1.67 V. The changes in redox potentials and the spectra of the compounds as a function of substituents attached on the β-ketone axial ligands were evaluated using linear free energy relationships. The thin-layer UV-visible spectroelectrochemistry indicates that phthalocyanine π-cation radicals and π-anion radicals were formed upon the first oxidation and first reduction, respectively. © ISUCT Publishing.