Structure of a (4 + 4)‐Coordinate Silicon Compound, a Precursor of Hypercoordinate Silyl Mono‐ and Dications

A tetracapped tetrahedron describes the geometry of the coordination environment of the silicon atom in 1; it is thus (4 + 4)-coordinate. Treatment of 1 with two equivalents of HC1 leads surprisingly to loss of H2 and formation of the corresponding chloride salt, whose centrosymmetric cation contains a six-coordinate silicon atom.