Neutral hyperconjugation and one-bond couplings between heavy atoms

Abstract

The relationship has been examined between bond order and one-bond couplings involving heavy atoms, as modulated by neutral hyperconjugation. Two systems have been studied in which either an aromatic ring or a double bond can influence, through hyperconjugation, the α and β bonds (respectively, Ci—C and Ci—M in =C-C-M). Hyperconjugation may be modulated by substituents on the aromatic ring or double bond or by placement of different atoms (M = C, Si, Ge, or Sn) at the β position. The α bond exhibits no relationship between coupling constant and neutral hyperconjugation, but the β bond shows a strong relationship.Key words: hyperconjugation, germanium, σ-π conjugation, silicon, tin.