two-electron bond three-centre

chemistry

Also known as: 3c,2e bond

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July 14, 2026

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A three-centre, two-electron bond is a type of chemical bond where two electrons are shared among three atoms. This concept is particularly useful in understanding the bonding in boranes, which are compounds of boron and hydrogen.1

In diborane (B₂H₆), for example, B–H–B bridges are formed, illustrating this type of bond. While molecular orbital theory describes the entire molecule, the idea of a three-centre, two-electron bond helps chemists visualize and rationalize the bonding in these electron-deficient compounds. This bonding model is also applicable to other boron compounds and their anions, leading to complex structures like closo-, nido-, and arachno-boranes, which can be predicted using Wade's rules.1

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chemical bonding
Boranes
…as an example of a three-centre, two-electron bond (a 3c,2e bond, as shown in Figure 19). They regard diborane as three atoms held together by a pair of electrons delocalized over three atoms but are aware that this semilocalized picture is only a part of the true picture.
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…as an example of a three-centre, two-electron bond (a 3c,2e bond, as shown in Figure 19). They regard diborane as three atoms held together by a pair of electrons delocalized over three atoms but are aware that this semilocalized picture is only a part of the true picture.
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organometallic compound
Simple alkyl ligands
…a cyclic intermediate involving a three-centre, two-electron bond where a hydrogen atom bridges between the carbon and the metal atoms.
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…a cyclic intermediate involving a three-centre, two-electron bond where a hydrogen atom bridges between the carbon and the metal atoms.
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