Frontier orbitals

Definition

Frontier orbitals are the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) in a molecule, playing crucial roles in determining how chemical reactions occur, especially in pericyclic reactions. They are key in understanding the reactivity and interaction between molecules in organic chemistry.

Related terms

Pericyclic Reactions: These are reactions that proceed through a cyclic transition state, allowing electrons to move smoothly between frontier orbitals across conjugated systems within a molecule.

Molecular Orbital Theory: This theory describes how atomic orbitals combine to form molecular orbitals, which are then occupied by electrons of a molecule, including both bonding and antibonding interactions.

Conjugated System: A system in organic chemistry where pi bonds or lone pairs are separated by single sigma bonds, allowing for delocalization of pi electrons across all adjacent aligned p-orbitals