Novel Heterocyclopentadienes. II

The dimerization of diphenylaeetylene by lithium metal has been investigated and shown to yield an active dilithium compound which may be used in the preparation of heterocyclic materials by condensation with metallic (or metalloid) dihalides. A series of monocyclic heterocyclopentadienes having the general structure I has been prepared. In this series, M equals S, P, As, Sb, C, Ge or Sn. The substituents R₁ and R₂ may be absent in the case of a divalent hetero atom or may be alkyl, aryl or halide in the case of tri- or tetravalent hetero atoms. Spiro compounds have been prepared having the general structural formula II in which M is either Ge or Sn.