Synthesis, structure, spectroscopic properties, and electrochemical behavior of mixed ligand bis(β-ketoesterato)zirconium (IV) and -hafnium (IV) phthalocyaninates

The synthesis of new zirconium and hafnium mixed ligand phthalocyanine complexes PcM(β-ketoester)2, where M–Zr (IV), Hf (IV); Pc – the dianion of phthalocyanine, and β-ketoester – the out planed ligand, is reported. The obtained complexes are characterized by 1H NMR, IR, UV–Vis spectroscopy and cyclic voltammetry. 1H NMR and elemental analysis confirm the substitution of two Cl atoms for two β-ketoester fragments to the central atom of the macrocycle. The data of 1H NMR, UV–Vis spectroscopy have allowed us to conclude that two β-ketoester ligands are in the cis geometry to the phthalocyanine plane. X-ray crystallography for bis(isopropyl 3-oxobutanoato)hafnium(IV)phthalocyanine confirms this conclusion. The central macrocycle of the phthalocyanine ligand is not exactly planar (deviations from the least-square plane exceed 0.15 Å) and has the conformation of an essentially flattened crown. The Hf(1) atom is 1.349(3) above this least-square plane. Cyclic voltammetry investigation shows that the introduction of two β-ketoester ligands to the central atom of phthalocyanine complex leads to both chemical and electrochemical stabilization of the whole Pc system.