The first spirobifluorenes which comprised of two binaphthyl moieties with silicon and germanium at the site of fusion were synthesized and fully characterized. The compounds were prepared by lithiation of 2,2′-dibromobinaphthyl (78 to -30°C) and subsequent treatment of the dilithio species with 0.5 equiv of silicon tetrachloride or germanium tetrachloride, followed by chromatography over silica gel. X-ray crystallography analysis revealed that both molecules possessed highly distorted structures, which resulted in a low barrier for interconversion between the two atropisomers. The barrier was calculated from the temperature dependency of the nuclear magnetic resonance spectra.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry