Versatile reaction modes of tetrasilyldisilenes with various reagents have been disclosed. Typically, tetrakis(t-butyl-dimethylsilyl)disilene 1b reacts with 1-alkenes and a 1-alkyne having allylic hydrogens to afford the corresponding eneaddition products, while a reaction of 1b with styrene gives the [2+2] cycloaddition product. In contrast to tetra-t-butyldisilene and tetramesityldisilene, a reaction of 1b with a 1,3-butadiene gives quantitatively the [4+2] cycloaddition product. In accord with the biradical nature of disilene as predicted theoretically, tetrasilyldisilene 1b reacts with haloalkanes to provide the corresponding 2,3-dichlorotetrasilane or 2- alkyl-3-chlorotetrasilane probably via radical mechanisms. Facile nucleophilic additions of water, methanol, and methyllithium to 1b are indicative of the high electrophilicity of 1b.