Tetratellura[36]octaphyrin(1.1.1.1.1.1.1.1)\nMetalation:\nFrom Dynamic Behavior to Rigid Chiral Figure-of-Eight Molecule; Activation\nof the C–Te Bond by Ruthenium

The large expanded telluraporphyrin, tetratellura[36]octaphyrin(1.1.1.1.1.1.1.1),\nwas synthesized in 7% yield by acid-catalyzed condensation of pyrrole\nwith 2,5-bis(phenylhydroxymethyl)tellurophene and subsequent oxidation.\nThe macrocycle acquires the chiral figure-eight conformation with\ntwo alternative spatial arrangements of the heterocyclic rings. The\nmolecule exhibits dynamic behavior in solution, which was studied\nby means of <sup>1</sup>H NMR spectroscopy. The reaction with chlorine\nled to a reversible oxidative addition at two distant tellurium atoms,\nwhich altered the preferred conformations. Metalation of the tetratellura[36]octaphyrin\nwith triruthenium dodecacarbonyl selectively activated two of the\neight Te–C bonds, resulting in the formation of an organometallic\ndiruthenium compound. During the reaction, two tellurophene rings\nwere converted to 1-ruthena-2-telluracyclohexadiene units containing\noctahedral ruthenium(II) centers. The rigid structure of this chiral\ncomplex allowed the separation of enantiomers.