Diradicaloid

{
  "id": "MLC-T-CHM-003245",
  "term": "Diradicaloid",
  "field": "Chemistry",
  "definition": "A closed-shell molecule that possesses a low-lying triplet state, exhibiting partial diradical character in its ground state. Unlike a true diradical, which has two non-interacting electrons in degenerate orbitals, a diradicaloid has a small energy gap between its singlet ground state and the first triplet excited state. This small singlet-triplet energy separation imparts unique chemical reactivity and spectroscopic properties that are intermediate between those of a stable closed-shell molecule and a pure diradical.",
  "synonyms": [
    "biradicaloid"
  ],
  "subject": "Organic and Biomolecular Chemistry",
  "see_also": [
    "diradicals"
  ],
  "references": [
    "PAC, 2007, 79, 293. 'Glossary of terms used in photochemistry, 3rd edition (IUPAC Recommendations 2006)' on page 325 (https://doi.org/10.1351/pac200779030293)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/diradicaloid/"
}