| Research Abstract |
There has been no stable, neutral heteraaromatic compounds containing heavier group 14 elements, and their structures and properties have not been revealed yet. In this project, we studied on the synthesis of new type of heteraaromatic compounds containing a heavier group 14 element by taking advantage of effective steric protection group, 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl (Tbt) and 2,6-bis[bis(trimethylsilyl)methyl]-4-[tris(trimethylsilyl)methyl]phenyl (Bbt) and elucidated their sturctures and properties. Based on these results, we revealed the aromaticity of these compounds.
We succeeded in the synthesis and isolation of the first stable silabenzene, 1-silanaphthalene, 2-silanaphthalene, 9-silaanthracene, 9-silaphenanthrene, germabenzene, 2-germanaphthalene, and 9-germaanthracene as stable crystals by taking advantage of Tbt and Bbt groups. The X-ray structural analyses, spectral data on NMR, UV/vis, and Raman spectroscopy, and theoretical calculations indicated that all these compounds are aromatic compounds as well as the corresponding carbon analogues. It was elucidated that these compounds underwent ready 1,2-or 1,4-addition towards the Si=C or Ge=C double-bond with H_2O, MeOH, and so on. Interestingly, the sila-and germabenzene were found to form the η^6-metallabenzene arene complexes with group 6 metals (Cr,Mo,and W).
We think that the new knowledge obtained in this project lays the foundations of the chemistry of heteraaromatic compounds containing heavier group 14 elements. We expect that novel properties and functions of heteraaromatic compounds containing heavier group 14 elements will be revealed on the basis of these results, showing the potential applicability. Such chemistry will be applied to not only the synthesis of novel functional compounds but also the novel catalysis.
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