Organolanthanoids : II. Preparation and identification of some organolanthanoid species in solution

The organolanthanoid derivatives R₂M (R  C₆F₅, M  Yb or Eu; R  $\text{o}$-HC₆F₄ or PhCC, M  Yb) have been prepared by reaction of the corresponding diorganomercury compounds with ytterbium or europium metal in tetrahydrofuran at room temperature, and ($\text{o}$-HC₆F₄)₂Yb has been obtained by an analogous reaction at 0°C. The compounds were identified by determination of the amounts of polyfluoroarene or phenylacetylene and lanthanoid ions formed on acidolysis of the filtered reaction mixtures. Reaction of samarium with bis(pentafluorophenyl)mercury and of ytterbium with bis(2,3,4,5-tetrafluorophenyl) mercury at room temperature gives more complex products including RMF₂, MF₂ and RMF derivatives (R  C₆F₅, M  Sm; R  $\text{o}$-HC₆F₄, M  Yb), polyfluoropolyphenyls, and more complex organometallic species. These are considered to be derived from decomposition of initially formed (C₆F₅)₂Sm, (C₆F₅)₃Sm, and ($\text{o}$-HC₆f₄)₂Yb derivatives. The decomposition paths include fluoride elimination to give polyfluorobenzynes, reduction of polyfluoroaryl groups by lanthanoid(II) species, and hydrogen abstraction from tetrahydrofuran.