Metalloporphycenes: Synthesis and characterization of (pentamethylcyclopentadienyl)ruthenium sitting-atop and π-complexes

Unprecedented porphycene complexes, containing a [RuCp*] (Cp*: pentamethylcyclopentadienyl) fragment accommodated in the central N₄ core or directly bonded to the "π-face" of the macrocycle have been prepared and fully characterized, including via single crystal X-ray diffraction analysis. The optical and electrochemical properties of these new families of compounds were examined in detail, revealing fluorescence in the case of the "sitting-atop" complexes for which the lifetime was determined. For both metal (M = Cu, Ni) porphycene derivatives with a "fused" ruthenocene moiety, strong electronic communication was observed through efficient photoinduced electron transfer from the ruthenocene unit to the macrocycle after laser flash photolysis, affording a charge-separated state. This ruthenocene-macrocycle communication was also confirmed by observation of strong spin-spin coupling in the EPR spectra of the one-electron oxidized species; this allowed for calculation of the distance between the two metal centers.