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A Tin Analogue of the Cycloheptatrienyl Anion: Synthesis, Structure, and Further Reduction to Form a Dianionic Species
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posted on 2020-02-24, 15:49 authored by Shotaro Ito, Takuya Kuwabara, Youichi IshiiThe
synthesis and electronic structure of a tin analogue of the
cycloheptatrienyl anion are described. The reaction of 5,5-diphenyldibenzo[b,f]stannepin with lithium at low temperatures
reductively cleaved a Sn–Ph bond to give a lithium salt of
the stannepinyl anion, the structure of which was established by X-ray
diffraction analysis. Elongating the reaction time resulted in further
reduction of the other Sn–Ph bond to generate a dilithium species,
the formation of which was confirmed by a trapping reaction using
MeI. Unlike general cycloheptatrienyl anions, the monoanionic species
was proved to be nonaromatic on the basis of the NMR and X-ray diffraction
studies. When the reduction was carried out at room temperature, decomposition
of the seven-membered ring followed by Z/E isomerization promoted by lithium proceeded to generate
(E)-2,2′-dilithiostilbene, which forms a dimer
in the crystalline state.
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Keywords
reaction timeTin Analoguedilithium speciesX-ray diffraction analysistemperatures reductivelyroom temperaturecycloheptatrienyl anionDianionic SpeciesX-ray diffraction studiesCycloheptatrienyl AnionSntin analoguelithium saltNMRstannepinyl anioncycloheptatrienyl anionsmonoanionic speciesseven-membered ringbond