Isolobal principle

Isolobal (from Greek: isos = equal, lobos = overlap ) is the name for electronic equivalent fragments within a molecule. The term was introduced by Roald Hoffmann and others 1976.

Molecular fragments are then " isolobal " if the number, symmetry, shape, and electron occupation of the frontier orbitals are the same and they have a similar energy.

The isolobal analogy allows an overall view of inorganic, organic and organometallic structures.

Examples

  • The CH3 fragment is isolobal to the Mn ( CO) 5 fragment; Ethan is isolobal to Mangandecacarbonyl
  • The CH2 fragment is isolobal to the Fe ( CO) 4 fragment; Cyclopropane is isolobal to Triosmiumdodekacarbonyl
  • The CH fragment is isolobal to Co ( CO) 3 fragment
  • The CH fragment is isolobal to BH - fragment
Isoelectronicity
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