## strain

https://doi.org/10.1351/goldbook.S06037
Strain is present in a @[email protected] or @[email protected] if the energy is enhanced because of unfavourable bond lengths, bond angles or dihedral angles ('@[email protected]') relative to a standard. It is quantitatively defined as the standard @[email protected] of a structure relative to a strainless structure (real or hypothetical) made up from the same atoms with the same types of bonding. (The @[email protected] of formation of cyclopropane is $$53.6\ \text{kJ mol}^{-1}$$, whereas the @[email protected] of formation based on three 'normal' @[email protected] groups, from acyclic models, is $$-62\ \text{kJ mol}^{-1}$$. On this basis cyclopropane is destabilized by ca. $$115\ \text{kJ mol}^{-1}$$ of @[email protected])
See:
molecular entity
,
molecular mechanics calculation
,
transition structure
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1168 [Terms] [Paper]