Structure of siloxene and layered polysilane (Si6H6)

Powder-x-ray-diffraction measurements on siloxene and calculations of the diffraction patterns for the three commonly proposed structures of siloxene (${\mathrm{Si}}_6$ ${\mathrm{H}}_6$ ${\mathrm{O}}_3$) clearly show that only a structure with silicon layers is ever observed. The formation of siloxene from ${\mathrm{CaSi}}_2$ is topotactic, with the Si layers remaining intact and with no oxygen insertion into these layers. Siloxene prepared at 0 °C has very little oxygen incorporated into the interlayer gaps, and can be described as hydrogen terminated silicon layers (${\mathrm{Si}}_6$ ${\mathrm{H}}_6$), which we call layered polysilane. Layered polysilane can be purified by reaction with aqueous HF and is pyrophoric on contact with air. In some sense, layered polysilane can be considered the silicon equivalent of graphite.