67. Covalent Bonding(13)- sp3d3 , sp3d4 Hybridization.

sp³d³ hybridization

The process of mixing one s- orbital, three p- orbitals, and three d-orbitals in an atom to form seven sp³  d³ hybrid orbitals of equivalent energy is called sp³ d³ hybridization.

EXAMPLE  1 – IODINE HEPTAFLUORIDE (IF₇)

Iodine is a p-block element and it has 7 valence electrons. Both iodine and fluorine are halogens and thus iodine heptafluoride is an interhalogen compound – a compound formed between two halogens. In this compound, iodine is the central atom that undergoes hybridization.

Iodine (53)  1s² 2s² 2p⁶ 3s² 3p6 3d¹⁰ 4s² 4p⁶ 4d¹⁰ 5s² 5p⁵  → Ground state

One s and two 5p electrons get excited to the vacant d-orbital, which gives rise to 7 unpaired electrons. The 5s,5p and 5d orbitals hybridise to form seven sp³  d³ hybrid orbitals.The molecule is then formed with 7 fluorine atoms.

The geometry of this molecule is pentagonal bipyramidal. Five F atoms are in one plane directed at corners of a pentagon (equatorial position), with a 72º angle between them. One F atom is above and one F atom below the plane of the pentagon(Axial positions). The angle between axial and equatorial F atoms is 90º.

The 3D structure can be represented as follows –

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sp³d⁴ hybridization

This type of hybridization is very rare as it demands the central atom to be bonded to eight different atoms/ligands. Very few elements show an oxidation state of more than +7 (e.g.- Mn+7). We shall not study this in detail as its occurrence is very rare. 

The key points to remember about the hybridization theory are –

• # of atomic orbitals mixed = # of atomic orbitals obtained.

• The electrons in unhybridized p orbitals form π bonds.

•  Hybrid orbitals form more stable bonds than pure atomic orbitals.

• The hybrid orbitals are always equivalent in energy and shape.

• The type of hybridization depends on how many atomic orbitals are mixed (this depends on the reaction conditions).

No.of substituents on the central atom	No. of hybrid orbitals	Hybrid orbitals	Type of hybridisation	Ideal Geometry	Bond Angle/s
7	7	one s + three p + three d	sp3d3	Pentagonal bipyramidal	72º, 90º
6	6	one s + three p + two d	sp3d2	Octahedral	90º
5	5	one s + three p + one d	sp3d	Triagonal bipyramidal (TBP)	120º, 90º
4	4	one s + three p	sp3	Tetrahedral	109.5º
3	3	one s + two p	sp2	Triagonal Planar	120º
2	2	one s + one p	sp	Ⅼinear	180º

With this post, we complete the study of all types of hybridizations. In the next post, we will study a new rule, which is important in our study on hybridization theory. Till then,

Be a perpetual student of life and keep learning…

Good day!!

Image source –

1. https://www.google.co.in/search?q=if7+geometry&source=lnms&tbm=isch&sa=X&ved=0ahUKEwix0Oe9x4XeAhWUUn0KHSUJBN8Q_AUIDigB&biw=1280&bih=649#imgrc=1n-BIkYsHJkM6M: