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Analisis spektra UV-Vis senyawa kompleks. Warna senyawa kompleks.

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Presentasi berjudul: "Analisis spektra UV-Vis senyawa kompleks. Warna senyawa kompleks."— Transcript presentasi:

1 Analisis spektra UV-Vis senyawa kompleks

2 Warna senyawa kompleks

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4 Konfigurasi elektronik atom multi-elektron Apakah makna konfigurasi 2p 2 ? n = 2; l = 1; m l = -1, 0, +1; m s = ± 1/2 Penataan elektron yang sesuai microstates beda energi karena tolakan antar elektron (inter-electronic repulsions)

5 Konfigurasi elektronik atom multi-elektron  pasangan RS Russell-Saunders (or LS) coupling Untuk tiap elektron 2p n = 2; l = 1 m l = -1, 0, +1 m s = ± 1/2 Untuk tiap atom multi-elektron L = total orbital angular momentum quantum number S = total spin angular momentum quantum number Spin multiplicity = 2S+1 M L = ∑m l (-L,…0,…+L) M S = ∑m s (S, S-1, …,0,…-S) M L /M S menyatakan microstates L/S menyatakan states (kumpulan microstates) Group microstates dengan energi yang sama disebut terms

6 Menentukan microstates untuk p 2

7 Spin multiplicity = 2S + 1

8 Menentukan harga L, M L, S, Ms untuk terms yang berbeda 1S1S 2P2P

9 Mengklasifikasikan microstates p 2 Spin multiplicity = # columns of microstates Next largest M L is +1, so L = 1 (a P term) and M S = 0, ±1 for M L = +1, 2S +1 = 3 3 P One remaining microstate M L is 0, L = 0 (an S term) and M S = 0 for M L = 0, 2S +1 = 1 1 S Largest M L is +2, so L = 2 (a D term) and M S = 0 for M L = +2, 2S +1 = 1 (S = 0) 1 D

10 Largest M L is +2, so L = 2 (a D term) and M S = 0 for M L = +2, 2S +1 = 1 (S = 0) 1 D Next largest M L is +1, so L = 1 (a P term) and M S = 0, ±1 for M L = +1, 2S +1 = 3 3 P M L is 0, L = 0 2S +1 = 1 1 S

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12 Energy of terms (Hund’s rules) Lowest energy (ground term) Highest spin multiplicity 3 P term for p 2 case If two states have the same maximum spin multiplicity Ground term is that of highest L 3 P has S = 1, L = 1

13 before we did: p2p2 M L & M S Microstate Table States (S, P, D) Spin multiplicity Terms 3 P, 1 D, 1 S Ground state term 3 P the largest M L  L spin multiplicity = Σcolumns or 2S+1, S the largest M S

14 single e - (electronic state)  multi-e - (atomic state)

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17 For metal complexes we need to consider d 1 -d 10 d2d2 3 F, 3 P, 1 G, 1 D, 1 S For 3 or more electrons, this is a long tedious process But luckily this has been tabulated before…

18 Transitions between electronic terms will give rise to spectra

19 Remember what we’re after ? Theory to explain electronic excitations/transitions observed for metal complexes

20 Selection rules (determine intensities) Laporte rule g  g forbidden (that is, d-d forbidden) but g  u allowed (that is, d-p allowed) Spin rule Transitions between states of different multiplicities forbidden Transitions between states of same multiplicities allowed These rules are relaxed by molecular vibrations, and spin-orbit coupling

21 Breakdown of selection rules

22 Group theory analysis of term splitting

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24 Free ion term for d 2 3 F, 3 P, 1 G, 1 D, 1 S Real complexes

25 Tanabe-Sugano diagrams d2d2 show correlation of spectroscopic transitions observed for ideal O h complexes with electronic states energy axes are parameterized in terms of Δ o and the Racah parameter (B) which measures repulsion between terms of the same multiplicity

26 d 2 complex: Electronic transitions and spectra only 2 of 3 predicted transitions observed

27 TS diagrams Other d n configurations d1d1 d9d9 d3d3 d2d2 d8d8

28 d3d3 Other configurations The limit between high spin and low spin

29 the spectra of d n hexaaqua complexes of 1 st row TMs

30 The d 5 case All possible transitions forbidden Very weak signals, faint color

31 symmetry labels

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36 Charge transfer spectra LMCT MLCT Ligand character Metal character Ligand character Much more intense bands

37 [Cr(NH 3 ) 6 ] 3+

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39 Determining  o from spectra d1d1 d9d9 One transition allowed of energy  o

40 Lowest energy transition =  o mixing Determining  o from spectra

41 Ground state mixing E (T 1g  A 2g ) - E (T 1g  T 2g ) =  o


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