Diborane is drawn with two boron atoms and four terminal hydrogen atoms in one plane, and two further hydrogen atoms bridging the boron atoms, one above and one below that plane. Which description of its bonding is correct?
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Each boron forms two normal 2c–2e bonds to terminal hydrogens. The two bridging hydrogens each share one electron pair across B–H–B, giving two three-centre two-electron (banana) bonds.
- B.
Diborane is electron-deficient: there are not enough electrons for six ordinary two-electron bonds plus the bridges.
- C.
The roles are reversed: the terminal bonds are normal two-electron bonds and the bridges are three-centre bonds.
- D.
There is no direct boron–boron bond; the two borons are held by the hydrogen bridges.
NCERT: Class 11 Chemistry (2022 edition), Chapter 11: The p-Block Elements