Molecular tailoring: a possible synthetic route to hexasilabenzene

The possible synthesis of hexasilabenzene was studied as the consecutive reaction of three disilyne units in order to find a suitable substituent. Although there is a reaction pathway which leads to hexasilabenzene in the case of hydrogen (A) and phenyl (B) groups, and it is thermodynamically and kinetically favourable, the reaction can easily proceed toward octasila species which makes it impossible to keep the synthesis under control and prepare hexasilabenzene. In contrast to this, using a methylated terphenyl (D) substituent, the addition of the third disilyne unit to the four-membered silicon ring (D5) is highly unfavourable because of the steric hindrance of the substituents. The terphenyl group (C), however, seems to be a perfect substituent because the reaction pathway leading to substituted hexasilabenzene consists of thermodynamically favourable steps and small activation barriers, and further reaction is hindered by the bulky substituents. We suggest synthesizing hexasilabenzene from terphenyl-halosilanes, performing reductive dehalogenation.