Stereogenic unit

{
  "id": "MLC-T-CHM-011375",
  "term": "Stereogenic unit",
  "field": "Chemistry",
  "definition": "A grouping of atoms within a molecule that serves as a focus of stereoisomerism, such that interchanging two ligands at that unit gives a stereoisomer. Three basic types exist: a central atom with distinguishable ligands, such as a carbon bearing four different groups; a double bond whose carbons each carry two different substituents; and a twisted four-atom chain that is not coplanar, as in hindered biaryls. Every enantiomer must contain at least one stereogenic unit, although molecules with stereogenic units need not be chiral.",
  "synonyms": [
    "stereogen",
    "stereoelement"
  ],
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "asymmetric",
    "central atom",
    "chiral",
    "chirality centre",
    "cis-trans isomers",
    "conformation",
    "enantiomer",
    "ligands",
    "stable",
    "stereoisomerism",
    "torsion angle"
  ],
  "references": [
    "PAC, 1996, 68, 2193. 'Basic terminology of stereochemistry (IUPAC Recommendations 1996)' on page 2219 (https://doi.org/10.1351/pac199668122193)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/stereogenic-unit/"
}