3-center-2-electron bond

A 3-center-2-electron bond is an electron deficient chemical bond where three atoms share two electrons. The combination of three atomic orbitals form one bonding, one non-bonding, and one anti-bonding molecular orbital. Since the two electrons go into the bonding orbital this constitutes a chemical bond between the three atoms. The resulting molecular orbital, when visualised in 3D, looks like a banana, hence it is often called a banana bond.

Related Topics:
Electron deficient - Chemical bond - Atomic orbital - Molecular orbital - 3D - Banana - Banana bond

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This type of bond is seen in many boron compounds, for example diborane, B2H6. The monomer BH3 is unstable since the boron atom is only surrounded by six valence electrons. To complete its octet, it shares electrons with a B-H bond in another molecule. This is also the case in trimethylaluminium (Al(CH3)3), where the methyl group is bridging.

Related Topics:
Boron - Diborane - Valence electron - Octet - Trimethylaluminium - Al - CH₃ - Methyl group

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