Laticyclic hyperconjugative interactions involving a relay of CH2 or CH2CH2 units. A new and important mechanism for transmitting interactions over large distances

Abstract

The results of ab initio MO calculations (STO-3G basis set) on the complexes (14) and (15) are reported. The CH₄ groups in (14a; n= 1–3) and (15a; n= 1–4) markedly affect the π levels of these systems by a process termed laticyclic hyperconjugation. Calculations on (14b–e) and (15b–e) reveal that hyperconjugative interactions in (14a) and (15a) can be as large as conjugation involving nonbonding orbitals, π MOs, or vacant p orbitals. The relevance of the role that hyperconjugation might play in long-range interactions is discussed. It is concluded that the efficacy of such interactions in molecules might very well depend critically on the presence of hyperconjugation and through-bond effects.