NEW DICHLOROSILANES, CYCLOTRISILANES, AND SILACYCLOPROPANES AS PRECURSORS OF INTRAMOLECULARLY COORDINATED SILYLENES

Three highly coordinated dichlorosilanes, 11a, 12, and 13, were synthe sized, and their structures were investigated in solution as well as i n the solid state (12 and 13). The reductive dehalogenation of 11a and 12 with magnesium yielded cyclotrisilanes 14 and 20, which are in equ ilibrium with silylenes 15 and 24 as shown by trapping and silylene-ex change experiments. Treatment of 13 with magnesium metal afforded a mi xture of benzosilacyclobutene 38 and disilane 40, which also was obtai ned by the thermolysis of silacyclopropane 44. Trapping experiments co rroborated the involvement of silylene 43 in these reactions.