Synthesis, electrochemistry and spectroscopic properties of ruthenium phthalocyanine and naphthalocyanine complexes with triphenylarsine ligands

Abstract

We present here the preparation of [PcRu(AsPh 3) 2 ] (1) and [{(tBu) 4 Nc}Ru(AsPh 3) 2 ] (2). These complexes are the first examples of metal phthalocyanine and naphthalocyanine complexes with axially-coordinated arsine ligands. Both complexes were characterised by spectroscopic methods. The AsPh 3 ligands readily dissociate in non-coordinating solvents, with 2 showing more rapid dissociation. The electrochemistry of the complexes was studied by cyclic voltammetry. Complex 1 displayed one reduction and two oxidation processes. All three processes are macrocycle centred. The redox behaviour of 1 is similar to that of ruthenium phthalocyanine complexes with pyridyl ligands. One reduction and three oxidation processes were observed for complex 2. The reduction and first oxidation are assigned to macrocycle centred processes. The UV-Vis spectra of both complexes recorded over time showed macrocycle-centred oxidation. The oxidation was hindered by degassing the solvent or adding excess AsPh 3 to the solution. We were not able to determine if the species being oxidised are the starting complexes, or if ligand dissociation leads to an easily oxidised five coordinate species.

Photocytotoxic activity of a nitrosyl phthalocyanine ruthenium complex — A system capable of producing nitric oxide and singlet oxygen

“…Oxidation or reduction in ruthenium phthalocyanine complexes may occur either at the central metal or at the phthalocyanine ring and has been described for a series of [Ru(pc)LL'] species [39,40]. [Ru(NO) (ONO)(pc)] controlled reduction potential electrolysis culminates in changes in the UV-visible spectrum.…”

Synthesis, molecular and electronic structures of half-sandwich ruthenium(II) complexes with pyrimidine-based ligands

“…The wide interest is this field originates from the very rich redox chemistry and photophysics of these compounds. Even small changes in the coordination environment around the ruthenium can play a key role in altering the redox properties of the complexes, and thus, complexation of ruthenium by various ligands is very interesting and has been widely studied [1][2][3][4].…”

Electrochemical Evidence of Intramolecular Electronic Communication in Zr and Hf Phthalocyanines Bearing Ferrocene-Containing β-Diketonato Axial Ligands: Structure of [PcHf(FcCOCHCOC6H5)2]

“…Second, consideration of the HOMO–LUMO gap of phthalocyanines having redox-silent metals coordinated in its central cavity, here Zr 4+ and Hf 4+ , is also relevant. The difference between E °′ of the first oxidation process (wave I) and E °′ for the first reduction process (wave III) is directly related to the HOMO–LUMO energy gap for metallophthalocyanines having redox-silent metal centers (zirconium and hafnium in this case) . The energy of the Q-band absorption is also related to the Q-band λ max value via the equation E = hc /λ.…”

“…The difference between E °′ of the first oxidation process (wave I) and E °′ for the first reduction process (wave III) is directly related to the HOMO–LUMO energy gap for metallophthalocyanines having redox-silent metal centers (zirconium and hafnium in this case) . The energy of the Q-band absorption is also related to the Q-band λ max value via the equation E = hc /λ. Since the Q-band absorption wavelength for the ferrocene-free acac-containing complexes 15 and 16 are for all practical purposes observed at the same wavelength as those of the ferrocene-containing complexes 1 – 8 , it can be concluded that the energies of the HOMO–LUMO gaps are almost the same for all these complexes.…”