Dilithio Spiro Zincacyclopentadienes and Dizinca[10]cycles: Synthesis and Structural Characterization

In this work, we
report the synthesis and molecular structures
of two kinds of organozinc metallacycles: dilithio spiro zincacyclopentadienes 3 and dizinca[10]­cycles 4. Both complexes 3 and 4 were obtained from the reaction of 1,4-dilithio-1,3-butadienes 1 with ZnX2 (X = Cl, Br) in THF. The molecular
structure of 3 was determined by single-crystal X-ray
structural analysis and shows a spiro ring skeleton in which two zincacyclopentadienes
are fused by a Zn­(II) atom. Complex 3 represents the
first well-defined examples of groups 12 metallacyclopentadienes.
The molecular structure of 4 contains a distorted ten-membered
dizincacycle. Multinuclear NMR measurements of 3 and 4 were conducted, and the structural transformations between
them were observed. In addition, the insertion reaction of these organozinc
metallacycles with S8 or Se were investigated to give their
corresponding thiophene or selenophene compounds.