1. HYBRIDIZATION IN SQUARE PLANER COMPLEXS
TOPIC:-HYBRIDIZATION IN SQUARE PLANER COMPLEX.
COURES :-M.Sc(Hons)CHEMISTR

2. ABSTRACT
HYBERDIZATION:-The phenomenon of mixing of orbitals of the same atom with slight difference in energies so as to redistribute their energies and give new orbitals of equivalent energy and shape. The new orbitals which get formed are known as hybrid.
TYPES OF HYBERDIZATION:-These are:-
SP HYBERDIZATION
SP2 HYBERDIZATION
SP3 HYBERDIZATION (Regular tetrahedron geometry)
SP3D HYBERDIZATION (Trigonal bipyramidal geometry )
SP3D2 HYBERDIZATION (Octahedral geometry )
SP3D3 HYBERDIZATION (Pentagonal bipyramedal geometry
DSP2 HYBERDIZATION (Square planer geometry )

3. INTRODUCTION Hybridization and the LE Model of Bonding
— Lewis structures of molecules
— prediction of geometry of molecules
— hybrid orbitals (sp3, sp2, sp, dsp3, d2sp3)
— interpretation of structure and bonding
Molecular Orbital Model of Bonding in Molecules
— molecular orbital diagrams
— bond order
— magnetism
Molecular Spectroscopy
— Electronic Spectroscopy
— Vibrational/Rotational Spectroscopies
— Nuclear Magnetic Resonance (NMR) Spectroscopy

4. Hybridization and the LE Model of Bonding
— Assume bonding involves only valence orbitals
— Methane, CH4:
Isolated atoms
Valence orbitals H
1s1 C
2s22p2 (2p: 2px, 2py, 2pz)
H atoms in CH4 will use 1s orbitals
Of the two types of orbitals (2s and 2p)
Which will C atoms use for bonding in CH4?
— If both are used: 2 different types of C-H bonds
(Contrary to experimental facts)
— Neither of the “native” atomic orbitals
of C atoms are used; instead, new hybrid orbitals are used.

5. Hybridization of atomic orbitals
The mixing of the “native” atomic orbitals to form
special orbitals for bonding is called hybridization.
The 4 new equivalent orbitals formed by mixing the
one 2s and three 2p orbitals are called sp3 orbitals.
The carbon atom is said to undergo sp3 hybridization,
i.e. is sp3 hybridized.
Energy-level diagram showing the sp3 hybridization
Energy 2p
hybridization
sp3 2s
Orbitals in C in
CH4 molecule
Orbitals in isolated
C atom

6. Native 2s and three 2p atomic orbitals characteristic of a free carbon atom are combined to form a new set of four sp3 orbitals.

7. Energy-level diagram showing the formation of four sp3 orbitals

8. Sp2 Hybridization Consider ethylene C2H4 molecule Lewis structure
— 12 valence e-s in the molecule
— What orbitals do the carbon atoms use to bond in ethylene?
— 3 effective electron pairs around each carbon
VSEPR model predicts a trigonal planar
geometry
sp3 orbitals with tetrahedral geometry and
109.5o angles will not work here.
120o angles

9. The plastics shown here were manufactured with ethylene.

10. The hybridization of the s, px, and py atomic orbitals results in the formation of three sp2 orbitals centered in the xy plane.

11. Energy-level diagram of sp2 hybridization
1 2s orbital +
2 2p (px, py) orbitals
3 sp2 orbitals
Energy-level diagram of sp2 hybridization E
Energy 2p 2p
hybridization
sp2 2s
C atom orbitals
in ethylene
Orbitals in isolated
C atom
Un-hybridized pz orbital
Carbon uses the sp2 hybridized orbitals for forming sigmal (σ)
bonds within the plane
The remaining 2pz orbital is used for forming the pi (π) bond.
Note that the double bond consists of one σ and one π bond.

12. When one s and two p oribitals are mixed to form a set of three sp2 orbitals, one p orbital remains unchanged and is perpendicular to the plane of the hybrid orbitals.

13. The sigma bonds in ethylene.

14. A carbon-carbon double bond consists of a sigma bond and a pi bond.

15. (a) The orbitals used to form the bonds in ethylene
(a) The orbitals used to form the bonds in ethylene. (b) The Lewis structure for ethylene.

16. .. .. Other sp2 hybridized carbon atoms
An atom surrounded by 3 effective electron pairs
uses sp2 hybridized orbitals for bonding.
Example
H2CO formaldehyde ..
Lewis Structure ..
— 12 valence electrons
— 3 effective pairs around C
Sp2 hybridized orbitals are used to form the C-H bonds
and the C-O σ bond, the un-hybridized 2pz orbital is used
to form the C=O π bond.

17. O=C=O sp Hybridization
Carbon in carbon dioxide, CO2 uses another type of hybridization (rather than sp2 or sp3) ‧‧ ‧‧
O=C=O ‧‧
2 hybrid orbitals required to meet the 180° (linear) geometry
requirement are sp orbitals.
2 effective pairs around C atom sp hybrid orbitals
3 effective pairs around O atom sp2 orbitals 2p 2p sp
Energy
Hybridization 1s
Orbitals in sp hybridized orbitals in CO2
Orbitals in a
free C atom

18. When one s orbital and one p orbital are hybridized, a set of two sp orbitals oriented at 180 degrees results.

19. The hybrid orbitals in the CO2 molecule

20. (a) Orbitals predicted by the LE model to describe (b) The Lewis structure for carbon dioxide

21. Other Examples of sp Hybridization
N2 molecule
N atom: 2s22p3 ：N N：
Lewis Structure
2 effective pairs around each N atom in the Lewis structure
– Linear (180°) geometry
– 2 sp orbitals for each N atom:
．1 sp orbital for forming the σ bond
．1 sp orbital for holding the lone pair
The remaining un-changed 2p orbitals are used to form
the 2 π bonds.
Each triple bond consists of one σ and two π bonds.

22. (a) An sp hybridized nitrogen atom (b) The s bond in the N2 molecule (c) the two p bonds in N2 are formed when

23. Consider the bonding in phosphorous pentachloride PCl5
dsp3 Hybridization
Consider the bonding in phosphorous pentachloride PCl5 ： ： ： ： ： ： ：
Lewis structure ： ：
(assuming d-orbital participation) ： ： ： ： ： ：
– 40 valence electrons in the molecule
– 5 electron pairs around the central atom P
．VSEPR predicts trigonal bipyramidal geometry
– one 3d orbital
one 3s orbital
three 3p orbital
a set of 5 dsp3 hybrid orbitals
oriented in a trigonal bipyramidal configuration
– the Cl atoms in PCl5 use sp3 orbitals to form the P-Cl bonds and
to hold the lone pairs
In general, when there are 5 effective pairs around an atom
it uses dsp3 orbitals.

24. A set of dsp3 hybrid orbitals on a phosphorous atom

25. The orbitals used to form the bonds in the PCl5 molecule

26. Arsenic pentafluoride
Other Examples of dsp3 Hybridization
Triiodide ion I3- ： ： ：
Lewis structure
[ I – I – I ]- ： ： ： ： ： ：
Arsenic pentafluoride
AsF5 ：
d2sp3 hybridization ： ： ： ： ： ： ： ：
Sulfur hexafluoride, SF6 ： ：
– 48 valence electrons
– 6 effective pairs around S atoms
– VSEPR model predicts Octahedral geometry
The 6 pairs lead to d2sp3 hybridization of s atom,
forming a set of 6 octahedrally oriented d2sp3 orbitals. ： ： ： ： ： ： ：

27. An octahedral set of d2sp3 orbitals on a sulfur atom

28. The relationship among the number of effective pairs, their spatial arrangement, and the hybrid orbital set required

29. The relationship among the number of effective pairs, their spatial arrangement, and the hybrid orbital set required (cont’d)

30. Turning to Square Planar Complexes
Most convenient to use a local coordinate system on each ligand with
y pointing in towards the metal. py to be used for s bonding.
z being perpendicular to the molecular plane. pz to be used for p bonding perpendicular to the plane, p^.
x lying in the molecular plane. px to be used for p bonding in the molecular plane, p|.

31. ML4 square planar complexes
ligand group orbitals and matching metal orbitals

32. ML4 square planar complexes
MO diagram
π- bonding
s-only bonding

33. SQUARE PLANER MOLECULE GEOMETRY
Idealized structure of a compound with square planar coordination geometry.
The square planar molecular geometry in chemistry describes the stereochemistry (spatial arrangement of atoms) that is adopted by certain chemical compounds .As the name suggests, molecules of this geometry have their atoms positioned at the corners of a square on the same plane about a central atom.

34. STRUCTURE OF SQUARE PLANER MOLECULE

35. Molecular Geometry bond length, angle determined experimentally
Lewis structures
bonding
VSEPR
geometry
Valence
Shell
Electron
Pair
Repulsion
octahedron
90o bond angles
small groups
big groups
trigonal bipyramid
equatorial
120o
axial
180o

36. tetrahedron
109.5o
trigonal planar
120o
linear
180o
geometry
apply to Chemistry

37. .. linear 180o BeCl2 valence e- = 2 + (2 x 7) = 16e- fewer than 8e- Cl
two
valence pairs on Be
bonding e-
linear molecule

38. .. .. linear 180o CO2 valence e- = 4 + (2 x 6) = 16e- C O C O two
valence pairs on C
ignore double bonds
single and double bonds same
molecular geometry
linear
molecular shape
linear

39. .. : .. : .. : trigonal planar 120o SO2 valence e- = 6+ (2 x 6) = 18e-
three
valence pairs on S
two bonding pairs
one lone pair
molecular geometry
trigonal
molecular shape
bent
< 120o

40. tetrahedral
109.5o
CH4
valence e- = 4+
(4 x 1)
= 8e- C H
four
valence pairs on C
109.5o
molecular geometry
tetrahedral
molecular shape
tetrahedral

41. : tetrahedral 109.5o NH3 valence e- = 5+ (3 x 1) = 8e- N H four
valence pairs on N
three bonding pairs
one lone pair
molecular geometry
tetrahedral
molecular shape
trigonal pyramid
< 109.5o

42. : tetrahedral 109.5o H2O valence e- = 6+ (2 x 1) = 8e- O H four
valence pairs on O
two bonding pairs
two lone pair
molecular geometry
tetrahedral
molecular shape
bent
< 109.5o

43. .. bipyramidal 120o and 1800 PCl5 P Cl valence e- = 5+ (5 x 7) = 40e-
five
valence pairs on P
180o
90o
molecular geometry
bipyramidal
molecular shape
bipyramidal
120o

44. : .. bipyramidal 120o and 1800 SF4 valence e- = 6+ (4 x 7) = 34e- S F
five
valence pairs on S
four bonding pairs
one lone pair
< 180o
molecular geometry
bipyramidal
molecular shape
seesaw

45. : .. bipyramidal 120o and 1800 ClF3 valence e- = 7+ (3 x 7) = 28e- Cl
five
valence pairs on Cl
three bonding pairs
two lone pair
molecular geometry
bipyramidal
molecular shape T
90o
180o

46. : .. bipyramidal 120o and 1800 ICl2- valence e- = 7+ (2 x 7) + e-
five
valence pairs on I
two bonding pairs
three lone pair on I
molecular geometry
bipyramidal
molecular shape
linear

47. : .. octahedral 90o BrF5 valence e- = 7+ (5 x 7) = 42e- Br F six
valence pairs on Br
five bonding pairs
one lone pair
molecular geometry
octahedral
molecular shape
square pyramidal

48. : .. octahedral 90o XeF4 valence e- = 8+ (4 x 7) = 36e- Xe F six
valence pairs on Xe
four bonding pairs
two lone pair
molecular geometry
octahedral
molecular shape
square planar

49. SUBSTITUTION IN SQUARE PLANER
Substitution at Square Planar Metal Complexes
Examples of Square Planar Transition Metal Complexes:
Ni(II) (mainly d8) Rh(I) Pd(II) Ir(I) Pt(II) Au(III)
General Rate Law:
Factors Which Affect The Rate Of Substitution
1. Role of the Entering Group
2. The Role of The Leaving Group
3. The Nature of the Other Ligands in the Complex
4. Effect of the Metal Centre

50. SUBSTITUTION IN SQUARE PLANER

51. GRAPH OF SQUARE PLANER SUBSTITUTION

52. REFERENCE
^ G. L. Miessler and D. A. Tarr. Inorganic Chemistry, 3rd Ed.,
Pearson/Prentice Hall..
Miessler and Tarr(inorgnic chemistry)

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