Biradical

{
  "id": "MLC-T-CHM-001344",
  "term": "Biradical",
  "field": "Chemistry",
  "definition": "A molecule with an even number of electrons and two radical centers that behave almost independently, leaving two electrons spread over two approximately nonbonding orbitals. Hund's rule favors the triplet state, but the lowest triplet lies below or only slightly above the lowest singlet, so some biradicals have triplet ground states, such as trimethylenemethane, and others singlet ones, such as p-benzyne. Species whose centers interact strongly are called biradicaloids.",
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "Boltzmann constant",
    "carbenes",
    "configuration",
    "diradicals",
    "molecular entity",
    "molecular orbital",
    "nitrenes",
    "singlet state",
    "triplet state",
    "valence"
  ],
  "references": [
    "PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1089 (https://doi.org/10.1351/pac199466051077)",
    "PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1322 (https://doi.org/10.1351/pac199567081307)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/biradical/"
}