Chapter 7
Table 7.1: Pure covalent and BTD salt structures of ortho-mercaptoazo compounds,
considered for DFT calculations.
R
X
R'
R
S
S
N
R'
X
N1
N
N1
(Pure covalent structure)
(BTD salt structure)
(A)
(B)
Name of ortho-mercaptoazo compounds
Entry
X
R
R′
I
Br
H
H
II
Br
H
CH3
4′-Methylazobenzene-2-sulfenyl bromide
III
Br
H
Cl
4′-Chloroazobenzene-2-sulfenyl bromide
IV
Br
H
NO2
4′-Nitroazobenzene-2-sulfenyl bromide
V
Br
NO2
CH3
4′-Methyl-2′-nitroazobenzene-2-sulfenyl bromide
VI
SCN
H
H
VII
SCN
H
CH3
4′-Methylazobenzene-2-sulfenyl thiocyanate
VIII
SCN
H
Cl
4′-Chloroazobenzene-2-sulfenyl thiocyanate
IX
SCN
H
NO2
4′-Nitroazobenzene-2-sulfenyl thiocyanate
X
SCN
NO2
CH3
4′-Methyl-2′-nitro-azobenzene-2-sulfenyl thiocyanate
XI
CN
H
H
XII
CN
H
CH3
4′-Methylazobenzene-2-sulfenyl cyanide
XIII
CN
H
Cl
4′-Chloroazobenzene-2-sulfenyl cyanide
XIV
CN
H
NO2
4′-Nitroazobenzene-2-sulfenyl cyanide
XV
CN
NO2
CH3
4′-Methyl-2′-nitroazobenzene-2-sulfenyl cyanide
Azobenzene-2-sulfenyl bromide
Azobenzene-2-sulfenyl thiocyanate
Azobenzene-2-sulfenyl cyanide
136
Chapter 7
Table 7. 2: ∆E (in kcal/mol) at B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p)
levels of theory in gas, ethanol and aqueous phases.
Entry
B3LYP/6-311++G(d,p)
MP2/6-311++G(d,p)
∆Egas
∆Eethanol
∆Eaqueous
∆Egas
∆Eethanol
∆Eaqueous
I
-8.96
-12.47
-12.61
-10.47
-14.02
-17.63
II
-9.21
-12.63
-12.78
-10.99
-14.76
-14.92
III
-8.37
-11.56
-11.70
-9.80
-13.09
-13.15
IV
-7.98
-10.74
-10.87
-8.74
-11.43
-11.56
V
-9.11
-11.49
-11.56
-9.10
-11.51
-11.59
VI
-4.38
-5.38
-5.41
-1.67
-2.49
-2.51
VII
-3.62
-5.07
-5.11
-2.67
-3.84
-3.86
VIII
-3.18
-4.35
-4.38
-2.20
-3.09
-3.11
IX
-2.95
-3.95
-3.98
-2.00
-2.73
-2.76
X
-3.11
-4.01
-4.04
-1.26
-1.94
-1.96
XI
-2.52
-1.86
-1.81
-0.44
0.14
0.18
XII
0.53
0.41
0.41
0.04
-0.10
-0.11
XIII
0.48
0.38
0.37
0.04
-0.07
-0.08
XIV
0.34
0.24
0.24
0.01
-0.07
-0.07
XV
1.82
1.66
1.65
-0.08
-0.38
-0.39
137
Chapter 7
Table 7.3: Calculated flow of electronic charge, ∆q at B3LYP/6-311++G(d,p) and
MP2/6-311++G(d,p) levels of theory in gas, ethanol and aqueous phases.
Entry
B3LYP/6-311++G(d,p)
MP2/6-311++G(d,p)
∆qgas
∆qethanol
∆qaqueous
∆qgas
∆qethanol
∆qaqueous
I
0.088
0.103
0.104
0.074
0.087
0.084
II
0.090
0.106
0.107
0.077
0.090
0.090
III
0.084
0.098
0.099
0.070
0.080
0.081
IV
0.077
0.089
0.090
0.063
0.071
0.072
V
0.080
0.091
0.092
0.068
0.075
0.075
VI
0.062
0.072
0.073
0.041
0.045
0.046
VII
0.065
0.076
0.077
0.046
0.052
0.052
VIII
0.057
0.066
0.066
0.039
0.043
0.043
IX
0.049
0.056
0.056
0.033
0.035
0.035
X
0.050
0.056
0.056
0.034
0.036
0.036
XI
0.010
0.015
0.015
0.004
0.006
0.006
XII
0.014
0.017
0.018
0.009
0.009
0.009
XIII
0.013
0.016
0.016
0.008
0.007
0.007
XIV
0.012
0.013
0.013
0.007
0.006
0.006
XV
0.006
0.013
0.013
-0.001
0.010
0.006
138
Chapter 7
Table 7.4: Free energy of solvation, ∆Gsol (in kcal/mol) at B3LYP/6-311++G(d,p) and
MP2/6-311++G (d,p) levels of theory in ethanol and aqueous phases.
B3LYP/6-311++G(d,p)
Entry
MP2/6-311++G(d,p)
∆Gsol,ethanol
∆Gsol,aqueous
∆Gsol, ethanol
∆Gsol, aqueous
I
-12.65
-6.79
-12.91
-7.06
II
-13.23
-6.72
-13.22
-6.71
III
-13.14
-6.60
-13.03
-6.49
IV
-13.37
-8.11
-11.91
-6.43
V
-14.77
-8.31
-13.75
-7.12
VI
-11.08
-5.47
-10.29
-4.64
VII
-11.72
-5.51
-10.86
-4.61
VIII
-11.62
-5.38
-10.77
-4.48
IX
-12.00
-6.98
-9.85
-4.59
X
-13.30
-6.99
-11.59
-5.08
XI
-9.34
-4.32
-7.97
-2.94
XII
-8.89
-3.31
-8.33
-2.72
XIII
-9.17
-3.55
-4.91
-2.99
XIV
-9.76
-5.41
-7.95
-3.37
XV
-10.92
-5.52
-9.31
-3.70
139
Chapter 7
Table 7.5: Variation of N=N1, S−N1 and S−X (X = Br, SCN, CN) bond lengths of
BTD salt structures at B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) levels of
theory.
Entry
B3LYP/6-311++G(d,p)
MP2/6-311++G(d,p)
N=N1(Å)
S−
−N1(Å)
S−
−X(Å)
N=N1(Å)
S−
−N1(Å )
I
1.26 (1.25)*
2.07
2.49 (2.26)
1.26 (1.25)
2.08
II
1.26 (1.25)
2.07
2.50 (2.26)
1.26 (1.25)
2.07
2.49
(2.26)*
2.50 (2.26)
III
1.26 (1.25)
2.09
2.47 (2.26)
1.26 (1.25)
2.10
2.47 (2.26)
IV
1.27 (1.25)
2.12
2.45 (2.26)
1.27 (1.25)
2.12
2.45(2.26)
V
1.26 (1.25)
2.08
2.47 (2.26)
1.26 (1.25)
2.08
2.47 (2.26)
VI
1.25 (1.25)
2.29
2.29 (2.13)
1.25 (1.25)
2.29
2.29 (2.13)
VII
1.26 1.25)
2.28
2.30 (2.13)
1.26 1.25)
2.28
2.30 (2.13)
VIII
1.26 (1.25)
2.32
2.27 (2.12)
1.26 (1.25)
2.32
2.27 (2.12)
IX
1.26 (1.25)
2.36
2.25 (2.12)
1.26 (1.25)
2.36
2.25 (2.12)
X
1.25 (1.25)
2.34
2.26 (2.12)
1.25 (1.25)
2.34
2.26 (2.12)
XI
1.26 (1.25)
2.62
1.72 (1.70)
1.26 (1.25)
2.62
1.72 (1.70)
XII
1.26 (1.25)
2.61
1.72 (1.70)
1.26 (1.25)
2.62
1.72 (1.70)
XIII
1.26 (1.25)
2.62
1.72 (1.70)
1.26 (1.25)
2.62
1.72 (1.70)
XIV
1.26 (1.25)
2.63
1.72 (1.70)
1.26 (1.25)
2.63
1.72 (1.70)
XV
1.25 (1.25)
2.63
1.72 (1.70)
1.25 (1.25)
2.63
1.72 (1.70)
(Values for pure covalent structures are shown in bracket).
140
S−
−X(Å)
Chapter 7
(I)
(II)
(III)
(IV)
(V)
(VI)
(VII)
(VIII)
Figure 7.1 continued
141
Chapter 7
(IX)
(X)
(XI)
(XII)
(XIII)
(XIV)
(XV)
Figure 7.1: Optimized BTD salt structures of ortho-mercaptoazo compounds at
B3LYP/6-311++G(d,p) level of theory.
142
Chapter 7
(I)
(II)
(III)
(IV)
(V)
(VI)
(VII)
(VIII)
Figure 7.2 continued
143
Chapter 7
(IX)
(X)
(XI)
(XII)
(XIII)
(XIV)
(XV)
Figure 7.2: Optimized pure covalent structures of ortho-mercaptoazo compounds at
B3LYP/6-311++G(d,p) level of theory.
144
Chapter 7
BTD salt form
pure covalent form
Gas phase LUMO energy (in a.u.)
-0.10
-0.11
-0.12
-0.13
-0.14
0
1
2
3
4
5
6
7
8
9 10 11 12 13 14 15 16
Entry no. in table 7.1
(a)
BTD salt form
pure covalent form
0.035
Gas phase LUMO energy (in a.u.)
0.030
0.025
0.020
0.015
0.010
0.005
0.000
-0.005
-0.010
-0.015
-0.020
-0.025
-0.030
-0.035
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Entry no. in Table 7.1
(b)
Figure 7.3: Variation of ε LUMO (in a.u) of BTD salt and pure covalent structures at (a)
B3LYP/6-311++G(d,p), (b) MP2/6-311++G(d,p) levels of theory in gas phase.
145
Chapter 7
Ethanol phase LUMO energy (in a.u.)
B T D s a lt fo rm
p u re c o v a le n t fo rm
-0 .1 0 5
-0 .1 1 0
-0 .1 1 5
-0 .1 2 0
-0 .1 2 5
-0 .1 3 0
-0 .1 3 5
-0 .1 4 0
0
2
4
6
8
10
12
14
16
E ntry n o. in T ab le 7 .1
(a)
BT D salt form
pure covalent form
Ethanol phase LUMO energy (in a.u.)
0.030
0.025
0.020
0.015
0.010
0.005
0.000
-0.005
-0.010
-0.015
-0.020
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
Entry no. in Table 7.1
(b)
Figure 7.4: Variation of ε LUMO (in a.u) of BTD salt and pure covalent structures at (a)
B3LYP/6-311++G(d,p) level of theory and (b) MP2/6-311++G(d,p) level of theory in
ethanol phase.
146
Chapter 7
B T D salt fo rm
p u re cov a le n t fo rm
0.030
Water phase LUMO energy (in a.u.)
0.025
0.020
0.015
0.010
0.005
0.000
-0.005
-0.010
-0.015
0
2
4
6
8
10
12
14
16
Entry no. in Table 7.1
(a)
BTD salt form
pure covalent form
0.030
Water phase LUMO energy (in a.u.)
0.025
0.020
0.015
0.010
0.005
0.000
-0.005
-0.010
-0.015
0
2
4
6
8
10
12
14
16
Entry no. in Table 7.1
(b)
Figure 7.5: Variation of ε LUMO (in a.u) of BTD salt and pure covalent structures at (a)
B3LYP/6-311++G(d,p) level of theory and (b) MP2/6-311++G(d,p) level of theory in
aqueous phase.
147
Chapter 7
(I)
(II)
(III)
(IV)
(V)
(VI)
Figure 7.6 continued
148
Chapter 7
(VII)
(VIII)
(IX)
(X)
(XI)
(XII)
Figure 7.6 continued
149
Chapter 7
(XIII)
(XIV)
(XV)
Figure 7.6: Shapes of LUMO of ortho-mercaptoazo compounds in BTD salt structures.
150
Chapter 7
(I)
(II)
(III)
(IV)
(V)
(VI)
Figure 7.7 continued
151
Chapter 7
(VII)
(VIII)
(IX)
(X)
(XI)
(XII)
Figure 7.7 continued
152
Chapter 7
XIII
XIV
XV
Figure 7.7: Shapes of LUMO of ortho-mercaptoazo compounds in pure covalent
structure.
153
Chapter 7
gas phase
ethanol phase
aqueous phase
Electrophilic Fukui function
0.10
0.08
0.06
0.04
0.02
0
2
4
6
8
10
12
14
16
Entry no. in Table 7.1
(a)
Figure 7. 8(a): Variation of electrophilic Fukui function in different phases at
B3LYP/6-311++G(d,p) level of theory.
154
Chapter 7
0.9
gas phase
ethanol phase
aqueous phase
Local softness (in a.u.)
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0
2
4
6
8
10
12
14
16
Entry no. in Table 7.1
(b)
Figure 8(b): Variation of local softness in different phases (at B3LYP/6-311++G(d,p)
level of theory.
155
Chapter 7
gas phase
ethanol phase
aqueous phase
Local electrophilicity (in a.u.)
0.028
0.024
0.020
0.016
0.012
0.008
0
2
4
6
8
10
12
14
16
Entry no. in Table 7.1
(c)
Figure 8(c): Variation of local electrophilicity in different phases at B3LYP/6311++G(d,p) level of theory.
156