**Hybridisation of Elements involving d Orbitals**

- The elements which contain d orbitals in addition to s and p orbitals form hybrid orbitals with s, p and d orbitals.
- The hybridisation involves either [3s, 3p and 3d] or [3d, 4s and 4p] (as the energies of these orbitals are comparable).
- However, since the difference in energies of 3p and 4s orbitals is significant, no hybridisation involving 3p, 3d and 4s orbitals is possible.

Type of hybridisation |
Atomic Orbitals Involved |
Spatial Orientation of Hybrid Orbitals |

sp³d |
s + \(\underbrace{~{{p}_{x}}+\text{ }{{p}_{y}}+\text{ }{{p}_{z}}}_{{}}\)+ \(\underbrace{{{d}_{z}}_{{}^\text{2}}}_{outer}\) |
Trigonal Bipyramidal |

d sp³ |
\(\underbrace{{{d}_{z}}_{{}^\text{2}}}_{Inner}\)+ s + \(\underbrace{~{{p}_{x}}+\text{ }{{p}_{y}}+\text{ }{{p}_{z}}}_{{}}\) |
Trigonal Bipyramidal |

sp³ d² |
s + \(\underbrace{~{{p}_{x}}+\text{ }{{p}_{y}}+\text{ }{{p}_{z}}}_{{}}\) +\(\underbrace{{{d}_{z}}_{{}^\text{2}}+{{d}_{x}}_{{}^\text{2}-\text{ }y{}^\text{2}}}_{outer}\) |
Octahedral |

d²sp³ |
\(\underbrace{{{d}_{z}}_{{}^\text{2}}+{{d}_{x}}_{{}^\text{2}-\text{ }y{}^\text{2}}}_{Inner}\)+ s + \(\underbrace{~{{p}_{x}}+\text{ }{{p}_{y}}+\text{ }{{p}_{z}}}_{{}}\) |
Octahedral |

dsp² |
\(\underbrace{{{d}_{x}}_{{}^\text{2}-\text{ }y{}^\text{2}}}_{Inner}\)+ s +\(\underbrace{~{{p}_{x}}+\text{ }{{p}_{y}}}_{{}}\) |
Square Planar |

sp³d³ |
s + p_{x} + p_{y} + p_{z} + d_{xy} + d_{yz} + d_{zx} |
Pentagonal Bipyramidal |

**1. sp ^{3}d hybridization:**

- One s-orbital , three p-orbitals and one d-orbital hybridise to give five degenerate sp
^{3}d hybrid orbitals which are then used to form bonds. - the 5 orbitals are directed towards the corners of a trigonal bipyramidal.
- Orbitals taking part in hybridization: ns, np and nd.

Ex: PCl5

P → 1S², 2S² 2P⁶, 3S² 3P_{x}¹ 3P_{y}¹ 3P_{z}¹ [Ground State]

P → 1S², 2S² 2P⁶, 3S² 3P_{x}¹ 3P_{y}¹ 3P_{z}¹ 3d¹ [Ground State]

**2. sp ^{3}d^{2} hybridization:**

- One s, three p and two d orbitals are involved in hybridisation to form the 6 degenerate sp
^{3}d^{2}hybrids. - The shape of the molecule would be octahedral.

Ex: SF_{6 }