A silicon analogue of a fused bicyclic borirene derivative

The replacement of all carbon atoms in aromatic rings with main-group elements to afford inorganic ring systems is highly desirable due to their distinct aromatic character. However, fused polycyclic main-group element rings are rare and the feasibility of aromaticity in such compounds has yet to be explored. To explore aromaticity in fused polycyclic main-group element rings, a stable di-silicon analogue of fused bicyclic borirene, namely bicyclo[1.1.0]-2,4-diborylenyldisil-1(3)-ene 5 was synthesized from an N-phosphinoamidinato chlorosilylene 3. Compound 5 consists of a bridgehead Si 00000000 00000000 00000000 00000000 11111111 00000000 11111111 00000000 00000000 00000000 Si double bond bonded with two bridging borons resulting in an unsaturated fused bicyclic skeleton. The bridgehead Si Si σ- and π-electrons and bridging Si-B σ-electrons are stabilized by both σ- and π-aromatic delocalization on the Si₂B₂ fused bicyclic ring.