sp3d Hybridization

sp³d Hybridization

sp³d hybridization is shown in phosphorus penta chloride (PCl₅). The grounds state and the excited state outer electronic configurations of phosphorus (Z=15) are represented below.

Now the five orbitals (i.e., one s, three p and one d orbitals) are available for hybridization to yield a set of five sp3d hybrid orbitals which are directed towards the five corners of a trigonal bipyramidal as depicted in the below.

 It should be noted that tall the bond angles in trigonal bipyramidal geometry are not equivalent. In PCl₅ the five sp³d orbitals of phosphorus overlap with the singly occupied p orbitals of chlorine atoms to form five P-Cl sigma bonds. Three P-Cl bond lie in one plane and make an angle of 120 with each other; these bonds are termed as equatorial bonds. The remaining two P-Cl bonds-one lying above and the other lying below the equatorial plane, make an angle of 90 with the plane. These bonds are called axial bonds. As the axial bond pairs suffer more repulsive interaction form the equatorial bond pairs, therefore axial bonds have been found to be slightly longer and hence slightly weaker than the equatorial bonds; which makes PCl₅ molecule more reactive.