sp³d and sp³d² Hybridisation
Hybridisation schemes involving d orbitals that give five trigonal bipyramidal or six octahedral hybrid orbitals.
Formula / equation
5 or 6 hybrids
Unit
degrees
In depth
These schemes describe expanded octets and are available only from period 3 onwards, where empty d orbitals lie close enough in energy. Modern calculations suggest d participation is smaller than the simple picture implies, with three-centre four-electron bonding contributing significantly, but the geometric predictions remain reliable.
Examples in the real world
PCl₅ is trigonal bipyramidal via sp³d; SF₆ is octahedral via sp³d²; IF₇ needs sp³d³.