Abstract:
In contrast to the wealth of physical functionality of benzene, chemically it is generally inert due to considerable aromatic stabilization energy. However, replacing a C-H moiety of benzene with a heavier main-group moiety significantly affects the physical and chemical properties of the cyclic-π-conjugated systems. Therefore, we are interested in the replacement of C–H moieties with moieties that contain heavier group 14 elements (E–R; E = Si, Ge, Sn, or Pb; R = organic substituent) in order to control the physical and chemical properties. Since Sekiguchi et al. have reported the synthesis of the first stable 1,2-disilabenzenes by the reaction of the stable disilyne, the chemistry of 1,2-dimetallabenzenes have been developed. We have also reported the synthesis of the stable 1,2- and 1,4-digermabenzenes by the analogous reactions, i. e., the reaction of the diaryldigermyne with alkynes. Herein, we report the synthesis of stable 1,2- and 1,4-disilabenzenes, and 1,2- and 1,4-digermabenzenes by the reactions of the stable disilyne and digermyne, TbbE≡ETbb (E = Si or Ge, Tbb = 2,6-[CH(SiMe3)2]2-4-t-Bu-C6H2), with terminal- and internal-alkynes. Their formartion mechanism and the electron distribution analyses of the obtained hetarenes will also be discussed.