Spectroscopic and Structural Study of Metal-Metal Bonded Metalloporphyrinic Derivatives: the Case of Rhodium-Indium

The synthesis and spectroscopic characterization of heterometallic porphyrinate derivatives containing rhodium- indium metal-metal bonds are reported. The investigated compounds are represented by the formula ((Porph)- RhIn(Porph')), where Porph and Porphare OEP, TPP, ‚-Cl4TPP, ‚-Cl8TPP, or TPyP. UV-Visible spectroscopy of the title complexes confirms the presence of a strong ﷿-﷿ interaction between the macrocycles in each derivative and denotes the effect of the nontransition metal in their optical features. For comparison purposes, a new bimetallic complex with a rhodium-thallium metal-metal bond is also presented. According to 1 H and 13 C NMR data, we were able to distinguish two major NMR regions: the endo- between the metal-metal bonded macrocycles and the exo-, which are characteristic features of porphyrinic complexes at very close proximity. X-ray absorption spectroscopy (XAS) structural characterization of Rh-In bond was performed on the ((OEP)RhIn(OEP)) complex, in the fluorescence mode, and we essentially focused on the metal-metal distance determination. Finally, the distance of 2.543(3) A was deduced from the X-ray structure of a new ((TPP)RhIn(TPyP)) derivative.