Hybridization-2

This ppt explains the geometries of molecules on the basis of hybridization involving s, p, d orbitals

1. Bonding in Molecules Part-III: Hybridization-II (Remedial Teaching Lecture-1) Prepared by D. R. Shinde Associate Professor in Chemistry Department of Chemistry P.D.E.A’s. Prof. Ramkrishna More Arts, Commerce and Science College Akurdi , Pune-411044

2. In this part we Will learn Types of Hybridization-Involving s, p and d Orbitals Examples to explain Hybridization-Involving s, p and d Orbitals Shapes and bond angels in molecules with Hybridization-Involving s, p and d Orbitals 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 2

3. Types of Hybridization-Involving s, p and d Orbitals i . One s + two p + one d orbital - form two dsp 2 hybrid orbitals ii. One s + three p + one d orbital - form five dsp 3 hybrid orbitals iii . One s + three p + two d orbital - form six d 2 sp 3 hybrid orbitals iv . One s + three p + three d orbital - form seven d 3 sp 3 hybrid orbitals 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 3

4. 1. dsp 2 hybridization : One s, two p and one d orbitals of same atom having nearly same energy mix with each other to form four dsp 2 hybrid orbitals. Four dsp 2 hybrid orbitals are oriented at the corners of the square plane. This gives angle between two hybrid orbitals 90˚ There are five types of d orbitals ( d xy , d xz , d yz , d x 2 – y 2 and d z 2 ). From these d x 2 – y 2 have suitable geometry and orientation hence it take part in dsp 2 hybridization + + S orbital p z and p x orbital orbitals d x 2 -y 2 orbital + - + - z x - - + + x y + - - + - + + - 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi , Pune 4 dsp 2 hybrid orbitals

5. Example: [Ni(CN) 4 ] 2-: In this complex , Ni(II) ion is central metal ion which undergo dsp 2 hybridization. Outer most shell Electronic configuration of ‘Ni (atomic number 28)’ ion is 3d 8 4s 2 , 4p In Complex Ni loss two electron from 4s orbital to form ‘Ni(II)’ ion. Thus, electronic configuration of Ni(II) ion is 3d 8 4s 4p ↑↓ ↑↓ ↑↓ ↑ ↓ ↑ ↓ ↑↓ ↑↓ ↑↓ ↑↓ During complex formation, Ni(II) ion undergoes excitation, where two unpaired electrons in 3d orbital pair with each other 3d 8 4s 4p ↑↓ ↑↓ ↑↓ ↑↓ ↓ ↑↓ ↑↓ ↑↓ ↑↓ Thus, one of the 3d i.e. 3d x 2 - y 2 orbital, 4s orbital and two 4p orbitals are empty. They undergo dsp 2 hybridization to form four dsp 2 hybrid orbitals. 3d 8 4s 4p ↑↓ ↑↓ ↑↓ ↑↓ ↓ ↑↓ ↑↓ ↑↓ ↑↓ dsp 2 hybridization 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 5

6. Each CN - ion donate its pair electron to Ni(II) ion to form coordinate bond. The electrons from the CN - are accommodated in empty hybrid orbitals of Ni(II) ion. The C of CN - ion consists of lone pair of electron on C atom which is used for bonding. : CN + - - + - + + - 90 ˚ : 4 CN + Four empty dsp 2 hybrid orbitals Lone pair of CN - ion + - - + - + + - : CN : CN : CN : CN Ni CN CN NC NC Square planar geometry of [Ni(CN)4] 2- complex ion Bond angle is 90 ˚ 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 6

7. 2. dsp 3 hybridization : One s, three p and one d orbitals of same atom having nearly same energy mix with each other to form four dsp 3 hybrid orbitals. As such it is result of sp 2 and dp hybridization. There are five types of d orbitals ( d xy , d xz , d yz , d x 2 – y 2 and d z 2 ). From these d z 2 have suitable geometry and orientation hence it take part in dsp 2 hybridization. + S orbital p z , P x and p x orbital orbitals d z 2 orbital + + - + - z x + - y dp hybridization p z + dz 2 orbitals sp 2 hybridization s + p x + p y orbitals p z and d z 2 orbital - + - + + - + - + - 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 7

8. - + - + - + + - + - Orbitals in Trigonal plane Orbitals along vertical axis, Perpendicular to trigonal plane + + - + - Axial orientation of two dp hybrid orbitals - + - + + - Trigonal planar orientation of three sp 2 hybrid orbitals Example: PCl 5 Molecule In PCl 5 Molecule central P has dsp 3 hybridization AO’s Ground state outer most shell Electronic configuration of P (At. No. 15) is 3d 3s 2 3p 3 ↑↓ ↑↓ ↑↓ ↑↓ ↓ ↑↓ ↑ ↓ ↑ ↓ ↑ ↓ 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 8

9. Excited state, outer most shell Electronic Configuration of P (At. No. 15) is 3d 1 3s 1 3p 3 ↑ ↓ ↑↓ ↑↓ ↑↓ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ Excited state, outer most shell Electronic Configuration of P in hybridized state is 3d dsp 3 hybrid orbitals ↑ ↓ ↑↓ ↑↓ ↑↓ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ dsp 3 hybridization - + - + - + + - + - Five dsp 3 hybrid Orbitals on P atom in excited state When reaction starts between P and Cl 2 gas, P atom undergoes excitation. One electron from 3s orbital is promoted to the higher energy 3d orbital. In excited state P atom undergoes dsp 3 hybridization 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 9

10. Cl (17) ground and excited state Outer shell electronic configuration : ↑↓ ↑↓ ↑↓ ↑ 3s 2 3p x 2 3p y 2 3p z 1 Cl atom has half filled 3p z orbital which take part in bonding. It form axial overlap with half filled hybrid orbital of P atom to form P-Cl sigma bond Thus, in excited state P consists of five half filled hybrid orbitals which take part in bonding with chlorine. 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 10

11. - + - + - + + - + - p z orbital of 5 Cl atom + - + 5 Hybrid orbitals of P atom - + - + - + + - + - + - + - + - + - + - Process of orbital overlap to form P-Cl sigma bonds PCl 5 Molecule : i ) Structure – Trigonal Bipyramidal, ii) Cl - P – Cl Bond angle - 120˚ in trigonal plane and 90 ˚ between trigonal plane and vertical axis. PCl 5 molecule P Cl 90 ˚ 120 ˚ 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 11

12. 3. d 2 sp 3 hybridization : One s, three p and two d orbitals of same atom having nearly same energy mix with each other to form six d 2 sp 3 hybrid orbitals. As such it is result of dsp 2 and dp hybridization. + - - + - + + - dsp 2 hybridization s + p x + p y + d x 2 - y 2 orbitals dp hybridization P z + d z 2 + - + - S orbital p z and p x orbitals d x 2 -y 2 orbital - - + + x y + - + - z x + - y d z 2 orbital Four dsp 2 hybrid orbitals Two dp hybrid orbitals 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi , Pune 12

13. Six d 2 sp 3 hybrid orbitals are oriented at the corners of the octahedron. This gives angle between two adjutant hybrid orbitals 90˚ d 2 sp 3 hybrid orbitals + - + - + - - + - + + - Octahedron dsp 2 hybrid orbitals dp hybrid orbitals + - + - + - - + - + + - + x y Z 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 13

14. Example of d 2 sp 3 hybridization od AO’s: S in SF 6 Molecule In SF 6 Molecule central S has d 2 sp 3 hybridized AO’s Ground state, outer most shell Electronic Configuration of S (At. No. 16) is 3d 3s 2 3p 4 ↑↓ ↑↓ ↑↓ ↑↓ ↓ ↑↓ ↑↓ ↑ ↓ ↑ ↓ Excited state, outer most shell Electronic Configuration of S is 3d 2 3s 2 3p 3 ↑ ↓ ↑ ↓ ↑↓ ↑↓ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ Excited state, outer most shell Electronic Configuration of S in hybridized state is 3d Six d 2 sp 3 hybrid orbitals ↑ ↓ ↑ ↓ ↑↓ ↑↓ ↓ ↑ ↓ ↑ ↓ ↑ ↓ ↑ ↓ d 2 sp 3 hybridization When reaction stats between S and F 2 gas, S atom undergoes excitation. One electron from 3s and one electron from 3p orbital is promoted to the higher energy 3d orbital. In excited state S atom undergoes d 2 sp 3 hybridization 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 14

15. F (9) ground and excited state Outer shell electronic configuration : ↑↓ ↑↓ ↑↓ ↑ 2s 2 2p x 2 2p y 2 2p z 1 F atom has half filled 2p z orbital which take part in bonding. It form axial overlap with half filled hybrid orbital of S atom to form S-F sigma bond. Thus, in excited state S consists of six half filled hybrid orbitals which take part in bonding with Fluoride. d 2 sp 3 hybrid orbitals + - + - + - - + - + + - 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 15

16. + - + - + - + - + - Process of orbital overlap to form S-F sigma bonds SF 6 Molecule : i ) Structure – Square planar Bipyramidal, ii) F – S – F Bond angle - 90˚ 6 p z orbital of 6 F atom + - Hybrid orbitals of ‘S’ atom + - + - + - - + - + + - + - - + + - - + - + + - + - S F 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 16

17. Sr. No Pure Orbitals used for hybridization Hybridi-zation Geometry Bond Angle Example 1 s, two p and one d dsp 2 Square Planar 90˚ [Ni(CN) 4 ] 2- [PtCl 4 ] 2 s, three p and one d dsp 3 Trigonal bipyramidal 120˚ and 90˚ PCl 5 3 s, three p and two d d 2 sp 3 Octahedral 90˚ SF 6 Summery 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 17

18. 02/08/2020 D. R. Shinde, Asociate Prof., P.D.E.A's. Prof Ramkrishna More College, Akurdi, Pune 18