Stereoelectronic effect

The stereoelectronic effect is the effect on molecular structures, physical properties and reactivities due to the molecules' electronic structures, in particular the interaction between atomic and/or molecular orbitals. Typical stereoelectronic effects with specific orbital overlaps generally lead to a specific molecular conformation or energy differentiation among various transition states that would lead to a particular reaction selectivity.

The stereoelectronic effect, along with the steric effect, inductive effect, mesomeric effect, etc., is one of the key theories in illustrating unusual selectivity, reactivity and stability cases in the course of organic chemistry. Its application has widely spread in organic methodology and organic synthesis. This topic is now entering biochemistry and pharmaceutical chemistry.

Stereoelectronic effect generally includes a donor–acceptor interaction. The donor is usually a higher bonding or nonbonding orbital and the acceptor is often a low-lying antibonding orbital as shown in the scheme below. As known from the orbital–orbital interaction requirement, if this stereoelectronic effect is to be favored, the donor–acceptor orbitals must have a low energy gap and they must retain antiperiplanar geometry to allow for perfect interacting direction.

Stereoelectronic effect contains a large variety of subtopics, including anomeric effects and hyperconjugation.

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