The dimerization reaction observed for the carbon tetrahedrane compound is also attempted for a tetrasilatetrahedrane. In this tetrahedrane the cage is protected by four so-called supersilyl groups in which a silicon atom has 3 "tert"-butyl substituents. The dimer does not materialize but a reaction with iodine in benzene followed by reaction with the tri-"tert"-butylsilaanion results in the formation of an eight-membered silicon cluster compound which can be described as a Si2 dumbbell (length 229 pm and with inversion of tetrahedral geometry) sandwiched between two almost-parallel Si3 rings.