12/4/2015

1

Advanced Inorganic Chemistry

Alireza Gorjiagorji@yazd.ac.ir

Department of Chemistry, Yazd University

1. Crystal Field Theory CFT

2. Ligand Field Theory LFT

3. Molecular Orbital Theory MOT

Bonding in Coordination Chemistry

پیوند در شیمی کوئوردیناسیون

2agorji@yazd.ac.ir

12/4/2015

2

3agorji@yazd.ac.ir

t2g

π-donor ligands

4agorji@yazd.ac.ir

12/4/2015

3

π-acceptor ligands

CN-, CO, PR3, C2H4

ML π-bonding (π-back bonding)

5agorji@yazd.ac.ir

agorji@yazd.ac.ir 6

12/4/2015

4

agorji@yazd.ac.ir 7

agorji@yazd.ac.ir 8

12/4/2015

5

agorji@yazd.ac.ir 9

agorji@yazd.ac.ir 10

12/4/2015

6

agorji@yazd.ac.ir 11

agorji@yazd.ac.ir 12

12/4/2015

7

agorji@yazd.ac.ir 13

agorji@yazd.ac.ir 14

12/4/2015

8

agorji@yazd.ac.ir 15

agorji@yazd.ac.ir 16

12/4/2015

9

agorji@yazd.ac.ir 17

agorji@yazd.ac.ir 18

12/4/2015

10

agorji@yazd.ac.ir 19

agorji@yazd.ac.ir 20

12/4/2015

11

agorji@yazd.ac.ir 21

agorji@yazd.ac.ir 22

12/4/2015

12

agorji@yazd.ac.ir 23

agorji@yazd.ac.ir 24

12/4/2015

13

agorji@yazd.ac.ir 25

1d-d transition

Ligand Field transition

The Electronic Spectra of Coordination Compounds

طیف الکترونی ترکیبات کوئوردیناسیون

26agorji@yazd.ac.ir

12/4/2015

14

The aim of this chapter is to demonstrate how to interpret the origins of the

electronic spectra of coordination comps and to correlate these spectra with bonding.

The spectrum of the d3 complex [Cr(NH3)6] in aqueous solution

The Electronic Spectra of Coordination Compounds

27agorji@yazd.ac.ir

28agorji@yazd.ac.ir

12/4/2015

15

29agorji@yazd.ac.ir

The classification of microstates

We start the analysis by setting up a table of microstates of the d2

configuration;have been only the microstates allowed by the pauli

principle have been included.The largest value of ML, which for a d2

configuration is +4. This state must belong to a term with L=4 (a G

term).

We can concluded that the terms of a 3d2 configuration are 1G, 3F, 1D, 3P, and 1S. These terms account for all 45 permitted states

Term Number of state1G 9x1 = 93F 7x3 = 211D 5x1 = 53P 3x3 = 91S 1x1 = 1

Total: 45

30agorji@yazd.ac.ir

12/4/2015

16

It is possible to identify the term of lowest energy by using Hund’s rule

1. For a given configuration, the term with the greatest multiplicity

lies lowest in energy. For the d2 configuration, this rule predicts that

the ground state will be either 3F or 3P.

2. For a term of given multiplicity, the greater value of L, the lower

the energy. In this case, the 3F term is lower in energy than 3P

term.The ground term of a d2 species such as Ti2+ is expected to be 3F.

Thus, for d2 the rules predict the order

3F 3P 1G 1D 1S

but the order observed for Ti2+ from spectroscopy is

3F 1D 3P 1G 1S

The energies of the term

31agorji@yazd.ac.ir

The Racah Repulsion Parameters

32agorji@yazd.ac.ir

12/4/2015

17

Energies of d2 free ion terms

3F 1D 3P 1G 1S

33agorji@yazd.ac.ir

Values for Racah Parameters

34agorji@yazd.ac.ir

12/4/2015

18

Splitting of d2 free ion terms in Octahedral field

35agorji@yazd.ac.ir

Splitting of d2 free ion terms in Octahedral field

36agorji@yazd.ac.ir

12/4/2015

19

37agorji@yazd.ac.ir

Splitting of dn free ion terms in Ligand fields

Tanabe-Sugano diagram for d2 config. Orgel diagram for d2 config.

38agorji@yazd.ac.ir

1

2

31

2

12/4/2015

20

3T1g

3T2g

3T1g

3A2g

Electronic Transitions of d2

ion in Octahedral Field

39agorji@yazd.ac.ir

4T1g

4T2g

4T1g

4A2g

Electronic Transitions of d7

ion in Octahedral Field

40agorji@yazd.ac.ir

d5+2

12/4/2015

21

Electronic spectrum of [Co(H2O)6]2+

41agorji@yazd.ac.ir

4T1g

4T2g

4T1g

4T1g (P)

4T1g

4A2g

3T2g

agorji@yazd.ac.ir 42

3T1g

3T1g

3A2g

4T1g

4T2g

4T1g

4A2g

d5+2d2

d2 , d7 Oh

12/4/2015

22

Hole Formalism in Electronic Transitions of dn ion

43

agorji@yazd.ac.ir

d7 d3

d2 d8

d2 d7 dn d10-ndn d5+n

Electronic spectrum of [Cr(OH2)6]3+

44agorji@yazd.ac.ir

1

2

3

4A2g

4T2g

4A2g

4T1g

4A2g

4T1g(P)

12/4/2015

23

3

Electronic spectrum of [Ni(OH2)6]2+

45agorji@yazd.ac.ir

3A2g

3T2g

3A2g

3T1g

3A2g

3T1g (P)

12

agorji@yazd.ac.ir 46

d2 , d7 Td

d2 , d7 Oh

d3 , d8 Td

d3 , d8 Oh

12/4/2015

24

agorji@yazd.ac.ir 47

d2 , d7 Ohd3 , d8 Oh

48agorji@yazd.ac.ir

Electronic Transitions of d1 ion in Octahedral FieldThe number of microstates possible for dX configuration is given by formula

)!(!

!

XNX

N

d1 case corresponds to X = 1 and N = 10 (maximum occupancy of the d-level). The number of microstates is then 10 which means that any of the five degenerate d-orbitals may be occupied by an electron with a spin of ½ or - ½.

The orbital angular momentum for Ti3+, L = 2, the spin S = 1/2 and the term is 2D

12/4/2015

25

2T2g

2Eg

Electronic Transitions of d1 ion in Octahedral Field

49agorji@yazd.ac.ir

lmax

Hole Formalism in Electronic Transitions of dn ion

50agorji@yazd.ac.ir

d4 d9

dn d10-n

d1 d6

dn d5+n

12/4/2015

26

agorji@yazd.ac.ir 51

Td Oh

2T2g

2E

Td Oh

agorji@yazd.ac.ir 52

d1 , d6 Td

d1 , d6 Oh

d4 , d9 Td

d4 , d9 Oh

12/4/2015

27

53agorji@yazd.ac.ir

12T2g

2Eg

2T2g

2Eg

15T2g

5Eg

Electronic spectrum of [Fe(OH2)6]2+

54agorji@yazd.ac.ir

5T2g

5Eg

12/4/2015

28

Electronic spectrum of [Cr(H2O)6]2+

15Eg(D) 5T2g

55agorji@yazd.ac.ir

5Eg(D)

5T2g

5

5

5

agorji@yazd.ac.ir 56

Electronic spectrum of [Cu(OH2)6]2+ 12Eg

2T2g

2Eg

2T2g

2

2

2

12/4/2015

29

d5 metal complexes• Terms of free d5 metal ions are 6S, 4G, 4F, 4D, 4P, 2I, 2H, 2G, 2G, 2F, 2F, 2D, 2D, 2D, 2P, 2S (16 terms, 252

microstates). The lowest energy term is 6S.

• In the octahedral ligand field the 6S term will NOT be split. It gives rise to a single 6A1g term.

• The 6A1g term is the ground state term at weak ligand fields. NO terms of the same multiplicity exists and thus NO spin-allowed e-e transition is possible.

• At strong ligand fields spin pairing occurs (t23e2 t2

5). As a result, the ground state term and the multiplicity change from 6A1g to 2T2g(I)

.

4G

(t2)5

(t2)4(e)1

(t2)2(e)3

(t2)1(e)4

octahedral and tetrahedral d5

2T2

6A1

4P

4T1

4T2

4E

4T1

4T1

4T2

4E

4A2

6S

free ion weak field strong field

57agorji@yazd.ac.ir

agorji@yazd.ac.ir 58

Configuration (example) Ground

state

Excited states w/same S # Abs.bands

d1 oct (Ti(H2O)63+), d9 tetr. 2T2

2E2 1

d2 oct (V(H2O)63+), d8 tetr. 3T1 (F) 3T2,

3T1 (P), 3A2 3

d3 oct (Cr(H2O)63+), d7 tetr. 4A2

4T2, 4T1 (F), 4T1 (P) 3

d4 oct (Cr(H2O)62+), d6 tetr. 5E2

5T2 1

d5 oct (Mn(H2O)62+) or tetr. 6A1 none 0

d6 oct (Fe(H2O)62+), d4 tetr. 5T2

5E2 1

d7 oct (Co(H2O)62+), d3 tetr. 4T1 (F) 4T2,

4T1 (P), 4A2 3

d8 oct (Ni(H2O)62+), d2 tetr. 3A2

3T2, 3T1 (F), 3T1 (P) 3

d9 oct (Cu(NH3)62+), d1 tetr. 2E2

2T2 1

Summary

12/4/2015

30

agorji@yazd.ac.ir 59

Summary

Electronic Transitions in Low Spin Complexes

agorji@yazd.ac.ir 60

low spin

high spin Orgel Diagram

Tanabe-Sugano Diagram

Tanabe-Sugano Diagram

12/4/2015

31

agorji@yazd.ac.ir 61

Tanabe – Sugano Diagram

d2 A=0 C/B=4.42

E(1S)= A+14B+7C E(1S)= 14B+7C E(1S)/B= 14+7C/B 44.9 52.9E(1G)= A+4B+2C E(1G)= 4B+2C E(1G)/B= 4+2C/B 12.8 20.8

E(1D)= A-3B+2C E(1D)= -3B+2C E(1D)/B= -3+2C/B 5.8 13.8

E(3P)= A+7B E(3P)= +7B E(3P)/B= +7 7 15E(3F)= A-8B E(3F)= -8B E(3F)/B= -8 -8 0

Tanabe – Sugano Diagram

agorji@yazd.ac.ir 62

12/4/2015

32

agorji@yazd.ac.ir 63

low spin high spin low spin high spin

agorji@yazd.ac.ir 64

low spin high spin low spin high spin

12/4/2015

33

agorji@yazd.ac.ir 65

agorji@yazd.ac.ir 66

The Nephelauxetic Effect[V(H2O)6]

3+. B = 610 cm-1

V3+(g) B = 861 cm-1

This value indicates that electron repulsions are weaker than in the free ion. This

weakening occurs because the occupied moleculer orbitals are delocalized over the

ligands and away from the metal.

nephelauxetic parameter = B (comp)/ B(free ion)

The values of depend on the metal ion and the ligand. They vary along the

nephelauxetic series:

Br- Cl- CN- NH3 H2O F-

A small value of indicates a large measure of d-electron delocalization on to the

ligands and hence a significant character in the complex.The softer ligand, the

smaller the nephelauxetic parameter.

12/4/2015

34

agorji@yazd.ac.ir 67

Determination of O and B

O

OO

d1, d3, d4, d6, d8, d9 1=O

d2, d7 3 - 1 =O

68agorji@yazd.ac.ir

CrF63-

14900, 22700 , 34400 cm-1

= 14900 cm-1

2 + 3 - 3 1 = 15B’ = 12400

15B’ = 12400

B’ ≈ 827 cm-1

d3, d81 =

2 = 7.5B’ + 1.5 - 0.5 [225 B’2+2-18B’]1/2

3 = 7.5B’ + 1.5 + 0.5 [225 B’2+2-18B’]1/2

(2 +3 -31)/15=B’

12/4/2015

35

V(H2O)63+ (d2)

1 = 17800 (3T1g 3T2g)

2 = 25700 (3T1g3T1g(P)) cm-1

The third expected transition 3 (3T1g(F) 3A2g) is far in the UV region and is masked by other absorptions. We can calculate the 3.

2/1 = 1.44

2:

2/B = 42(approximately): B= 2/42 = 25700cm-1/42 = 610 cm-1

1:

1/B = 29 (approximately): B= 1/29 = 17800 cm-1/29= 610 cm-1

Since o/B= 31, o= 31xB = 31x 610 cm-1 = 19000cm-1

3 ≈ (60)(610)=37210 cm-1

69agorji@yazd.ac.ir

1

2

UV/VIS spectra of three

chromium(III) complexes:

a) [Cr(en)3]3+

b) [Cr(ox)3]3-

c) [CrF6]3-

look for the shift of the two

absorption peaks 1 and 2

to lower frequencies.

a)

b)

c)

70agorji@yazd.ac.ir

a) [Cr(en)3]3+

b) [Cr(ox)3]3-

c) [CrF6]3-

12/4/2015

36

agorji@yazd.ac.ir 71

[Ni(en)3]2+(purple)

9000 cm-114000 cm-1

25000 cm-1

[Ni(H2O)6]2+(green)

B1g B2g

B1g Eg

Free ion term Oh D4h

When degenerate orbitals are asymmetrically occupied, J-T distortions arelikely

72agorji@yazd.ac.ir

John-Teller Distortion in Spectrum

12/4/2015

37

Eg A1gEg B1g

73agorji@yazd.ac.ir

12T2g

2Eg

2- Charge Transfer Transitions

agorji@yazd.ac.ir 74Ligand to Metal Charge Transfer Metal to Ligand Charge Transfer

12/4/2015

38

agorji@yazd.ac.ir 75

Ligand to Metal Charge Transfer (LMCT)

Ligand to Metal Charge Transfer

agorji@yazd.ac.ir 76

Ligand to Metal Charge Transfer (LMCT)

12/4/2015

39

agorji@yazd.ac.ir 77

Metal to Ligand Charge Transfer (MLCT)

Metal to Ligand Charge Transfer

agorji@yazd.ac.ir 78

Intensity & Selection Rule

Bear-Lambert

A: جذب

b: cm طول مسیرعبور نور

A = log(I0/I)

: M-1cm-1 ضریب جذب مولی

c: M غلظت

A = bc

A

l

12/4/2015

40

Intensity & Selection Rule

agorji@yazd.ac.ir 79

i

j Transition Moment Integral

0

0 dO ji

Forbiden

Allowed

غیر مجاز

مجاز

اربیتیاسپینی

g g

u u

غیر مجاز

S0غیر مجاز

agorji@yazd.ac.ir 80

Intensity & Selection Rule

اسپین تقارن (M-1cm-1)

d-d (Oh) مجاز

(S=0)

غیرمجاز

g g

20-200

d-d (Td) مجاز

(S=0)

مجاز >250

d-d غیرمجاز

(S0)

<1

CT مجاز

(S=0)

مجاز 1000-50000

12/4/2015

41

agorji@yazd.ac.ir 81

The spectrum of the d3 complex [Cr(NH3)6] in aqueous solution

The Electronic Spectra of Coordination Compounds

Electronic spectrum of [Mn(H2O)6]2+

Why is absorption by [Mn(H2O)6]2+

so weak?6A1Excited states is no spin-allo-wed absoption, may be very weakforbidden transitions to excited stateof spin multiplicity other than 6

82agorji@yazd.ac.ir

S0 غیر مجازاسپین

12/4/2015

42

83agorji@yazd.ac.ir

Vibronic Coupling

Absorption

, cm-12500012500

84agorji@yazd.ac.ir

Absorption of a TMC in the UV and visible regions results from transitions of electrons between the energy levels available in the metal complex.

Of our interest will be:

1) The number of absorption bands

2) The energy of absorption bands

3) The intensity of absorption bands

4) The band width of absorption bands

1

2

12/4/2015

43

agorji@yazd.ac.ir 85

agorji@yazd.ac.ir 86

12/4/2015

44

agorji@yazd.ac.ir 87

agorji@yazd.ac.ir 88

12/4/2015

45

agorji@yazd.ac.ir 89

agorji@yazd.ac.ir 90

12/4/2015

46

agorji@yazd.ac.ir 91

agorji@yazd.ac.ir 92