Synthesis, spectroscopy, and electrochemical behavior of a novel supramolecular copper-tetrapyridylporphyrazineruthenium cluster

A novel supramolecular complex displaying extended electronic interactions was obtained by combining the ruthenium cluster [Ru 3 O(Ac) 6 (py) 2 ] + species with the π-conjugated tetrapyridylporphyrazine molecule. The supramolecular species featured a porphyrazine center attached to four ruthenium clusters and was characterized by electronic and resonance Raman spectroscopy, as well as by cyclic voltammetry and spectroelectrochemistry. The FTIR spectra were essentially composed of vibrational peaks of the ruthenium cluster species, while the vibrational peaks of the tetrapyridylporphyrazine chromophore dominated the Raman spectra. The observed non-coincidence of the FTIR and Raman signals corroborates the centrosymmetric molecular structure proposed for this compound. At the same time, the electrochemistry in the potential range of -2 to 2 V (vs Ag/Ag + ) was marked by the redox processes involving the peripheral ruthenium cluster species. The change in their redox states produced dramatic effects in the Raman profiles, reflecting the electronic distribution in the porphyrazine core through p-backbonding effects induced by the metal clusters.