Molecule that has fewer valence electrons than required for forming normal two-center two-electron chemical bonds and thus contains multicenter chemical bonds.
Notes: - Binding of atoms into molecules, clusters and macroscopic bodies in electron-deficient compounds is mediated by delocalized electrons, each being shared by three or more atoms.
- Metals are typical electron-deficient compounds in which extreme delocalization of electrons across the whole macroscopic body exists.
- Boron, boranes, carboranes and related compounds are typical compounds with electron-deficient molecules in which boron and some other atoms are bound by multicenter two-electron bonds, such as by the two-electron three-center bond in which two electrons bind three atoms.
See also: extent of electron delocalization, electron-rich molecule
Source:
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)