# Hybridisation – II

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 + px + py + pz + dxy + dyz + dzx Pentagonal Bipyramidal

1. sp3d hybridization:

• One s-orbital , three p-orbitals and one d-orbital hybridise to give five degenerate sp3d 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 3Px¹ 3Py¹ 3Pz¹   [Ground State]
P → 1S², 2S² 2P⁶, 3S² 3Px¹  3Py¹ 3Pz¹ 3d¹   [Ground State]

2. sp3d2 hybridization:

1. One s, three p and two d orbitals are involved in hybridisation to form the 6 degenerate sp3d2 hybrids.
2. The shape of the molecule would be octahedral.
Ex: SF6