A Disilene Base Adduct with a Dative Si–Si Single Bond

An experimental and theoretical study of the base‐stabilized disilene 1 is reported, which forms at low temperatures in the disproportionation reaction of Si 2 Cl 6 or neo ‐Si 5 Cl 12 with equimolar amounts of NMe 2 Et. Single‐crystal X‐ray diffraction and quantum‐chemical bonding analysis disclose an unprecedented structure in silicon chemistry featuring a dative Si→Si single bond between two silylene moieties, Me 2 EtN→SiCl 2 →Si(SiCl 3 ) 2 . The central ambiphilic SiCl 2 group is linked by dative bonds to the amine donor and the bis(trichlorosilyl)silylene acceptor, which leads to push–pull stabilization. Based on experimental and theoretical examinations a formation mechanism is presented that involves an autocatalytic reaction of the intermediately formed anion Si(SiCl 3 ) 3 − with neo ‐Si 5 Cl 12 to yield 1 .