Effects of oxygen atom in the side chain on physical and optical properties of dodecapentoxypentasilane

The effects of the alkoxy side chain on the conformation of oligosilane have been studied for perpentoxypentasilane. The UV-absorption maxima shifted extremely to a shorter wavelength than that of peralkyloligosilane. Molecular dynamics and ab initio MO calculations showed that the excitation energy of the twisted structure for peroxyloligosilane (a model of perpentoxypentasilane) was smaller than that of permethyloligosilane, because of the interaction between the n orbital of the oxygen atom and the σ orbital of the Si–Si bond. The Coulomb repulsion energies between the oxygen atoms greatly affect the stability of the twisted conformation of the silicon backbone.