Reduction of Disilane ( t Bu 3 Si)Br 2 Si‐SiBr 2 (Si t Bu 3 ) in Presence of C 2 H 4 : A Mechanistic Approach

The reduction of R*–SiBr 2 –SiBr 2 –R* ( 2 ) with NaR* (R* = supersilyl = Si t Bu 3 ) in presence of C 2 H 4 provides a white crystalline solid (η 2 ‐C 2 H 4 )R*Si–SiR*(Br)(CH 2 –CH 2 –R*) ( 3 ) characterized by X‐ray diffraction analysis. Compound 3 is accompanied with an impurity of R*(Br) 2 Si–Si(Br)(R*)(CH 2 –CH 2 –R*) ( 4 ). The formation of 3 and 4 runs complicated because of several reactive partners. However, reduction of 2 with sodium naphthalenide in presence of ethene runs straightforward with formation of a mixture of tetrahedrane R* 4 Si 4 ( 1 ) and bis(silirane) R*(η 2 ‐C 2 H 4 )Si–Si(η 2 ‐C 2 H 4 )R* ( 5 ). The latter is formed by [1+2]‐cycloaddition reaction of intermediate disilyne R*Si≡SiR* with ethene. Compound 5 has been characterized by X‐ray structure determination. The 1 H NMR spectrum of the silacyclopropane ring protons shows AA′BB′ complex spectrum comprising of 2 sets each of 12 transitions.