Silyl-Substituted 1,4-Disila(Dewar benzene): New Synthesis and Unexpected Insertion of CO into the Si−Si Bond To Form a Disilyl Ketone

The silyl-substituted 1,4-disila(Dewar benzene) ( 1 ) was synthesized by the reduction of the corresponding dichloride 2 with 2.2 equiv of KC 8 in THF. The irradiation of 1 with light of wavelength λ > 320 nm in THF under a CO atmosphere produced the cyclic disilyl ketone 3 by the insertion of CO into the central Si−Si bond, whereas the photolysis of 1 in cyclohexane- d 12 afforded the silyl-substituted 2,5-disilabenzvalene 4 by intramolecular isomerization.