Silynes (RC≡SiR′) and Disilynes (RSi≡SiR′): Why Are Less Bonds Worth Energetically More? The research is supported by an Israel Science Foundation (ISF) and a Niedersachsen grant (to S.S.), by a U.S.–Israel Binational Science Foundation (BSF) grant (to Y.A.) and by the Minerva Foundation. S.S. and F.O. thank the European Union for a Marie Curie Fellowship (Contract number: MCFI-1999-00145). S.S. and D.D. thank P. C. Hiberty for the helpful advice.

Abstract

Bond stabilization through bending! Valence bond analysis shows that the σ frames of 1–3 (1: E = Si, E′ = C; 2: E = E′ = Si; 3: E = E′ = C) are stabilized by trans bending (B), while π bonding is weakened. In acetylene (3) π bonding overrides the σ frame and establishes a linear molecule (3 L). In contrast, the σ frames dominate in silyne (1) and disilyne (2) and lead to trans‐bent structures (1 B and 2 B).