Electron-deficient molecule

{
  "id": "MLC-T-CHM-003747",
  "term": "Electron-deficient molecule",
  "field": "Chemistry",
  "definition": "A molecule with too few valence electrons to give every bond the usual two-center two-electron form, so some bonding electrons are shared by three or more atoms in multicenter bonds. Boranes, carboranes and many clusters are examples. Diborane, B2H6, has only 12 valence electrons, two short of the 14 that seven conventional two-center bonds would need, and its two bridging hydrogen atoms are held by three-center bonds.",
  "subject": "Polymer",
  "see_also": [
    "delocalization of electrons",
    "electron-rich molecule",
    "extent of electron delocalization"
  ],
  "references": [
    "PAC, 2022, 94, 15. 'Glossary of terms relating to electronic, photonic and magnetic properties of polymers (IUPAC Recommendations 2021)' on page 28 (https://doi.org/10.1515/pac-2020-0501)"
  ],
  "url": "https://mlchart.com/terminology/chemistry/electron-deficient-molecule/"
}