Silylene and Disilene Additions to an Octa-1,3,5,7-tetrayne: Formation of a C−C-Linked Quatersilirene^1,2

Tetra-tert-butyldisilene and di-tert-butylsilylene (1), generated by photolysis of hexa-tert-butylcyclotrisilane, react with 1,8-di-tert-butylocta-1,3,5,7-tetrayne to furnish a C−C-linked bis(disilacyclobutene) derivative with terminal alkynyl groups 7 and a quatersilirene 8 by addition of 1 to all C−C triple bonds. Upon prolonged irradiation, 8 rearranges partly to the 2,5-disilabicyclo[2.2.0]hexa-1(6),3-diene with terminal silirene groups 9. The structures of 7, 8, and 9 were determined by X-ray crystallography.