Three-Centre Two-Electron Bond
A bond in which a single pair of electrons is shared between three atoms rather than two.
Formula / equation
A···H···B
Unit
kJ/mol
In depth
Such bonds arise in electron-deficient compounds that have too few valence electrons for a conventional structure. The bonding pair occupies a molecular orbital spanning all three atoms, giving a bent, banana-shaped electron distribution that classical Lewis theory cannot represent.
Examples in the real world
The two bridging B–H–B bonds in diborane B₂H₆, and the methyl bridges in Al₂(CH₃)₆.