研究室工作进展 Jun. 9th, 2019

Metallacycles are important building blocks and metal-mediated intermediates both in organometallic chemistry and organic synthesis. As one class of significant five-membered metallacycles, metallacyclopentadienes have received considerable attentions because of their distinctive structures and wide applications. Although many metallacyclopentadienes covering main-group metals and transition metals have already been successfully synthesized and characterized, metallacyclopentadienes of group 12 metals have not been reported yet.

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 of complexes 3 and 4were obtained from the reaction of 1,4-dilithio-1,3-butadienes 1 with ZnX₂ (X = Cl, Br) in THF. The molecular structure of 3 determined by single-crystal X-ray structural analysis 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.