Synthesis and Isolation of a Silylsilicate Containing Two Pentacoordinated Silicon Atoms by Monoprotonation of a Disilicate and Monodeprotonation of a Disilane

A silylsilicate, which is an intermediate in double protonation of a disilicate bearing two sets of a C,O-bidentate ligand at two pentacoordinated silicon atoms to give a disilane, was synthesized and isolated. The X-ray crystallographic analysis of both the silylsilicate and the disilane revealed intramolecular O···Si coordination, giving the silicon atoms pentacoordinated states. In the silylsilicate, the Si1–O2 and Si2–O3 bonds are almost in parallel. Deprotonation of the silylsilicate, which was also prepared by monodeprotonation of the disilane, gave the disilicate. The oxidation potential and UV/vis absorption maximum are both intermediate between those of the disilicate and the disilane, reflecting the changes in the charges.