The C=N center dot center dot center dot C-X sigma-hole interaction acts as a conformational lock

An interesting C=N center dot center dot center dot C-X conformation lock, which determines the linear alignment of the C=N and C-X fragments, has been found for the first time and is rationalized by density functional theory calculations. Second-order perturbation theory analysis based on the NBO method further reveals that the nature of the C=N center dot center dot center dot C-X interaction is mainly the lp(C=N) -> sigma*(C-X) interaction.