Conductometric Studies of Thermodynamics of Complexation of Co2+, Ni2+, Cu2+, and Zn2+ Cations with Aza-18-crown-6 in Binary Acetonitrile-Methanol Mixtures
Table 1
Formation constants for different M2+-A18C6 complexes in various AN-MeOH mixtures.
Cationa
wt% AN
Log
10°C
20°C
30°C
40°C
Co2+ (1.50)
100
5.66
0.76
5.50
1.11
5.27
1.48
5.19
1.69
80
3.87
1.60
3.89
1.95
3.79
1.87
3.90
2.41
60
2.82
0.10
2.90
0.15
2.98
0.25
2.91
1.35
40
2.83
0.11
2.87
0.14
2.83
0.15
2.86
0.25
Ni2+ (1.38)
100
5.47
0.54
5.49
0.60
5.28
0.63
5.05
0.72
80
3.73
1.09
3.91
1.81
3.95
2.14
4.00
2.72
60
2.90
0.12
2.94
0.18
3.06
0.69
3.14
0.44
40
2.96
0.17
2.99
0.21
3.01
0.23
3.06
0.30
Cu2+ (1.54)
100
7.44
0.09
7.77
0.07
7.48
0.09
7.63
0.07
80
3.39
0.71
3.47
0.94
3.53
1.16
3.63
1.73
60
3.11
0.31
3.14
0.37
3.17
0.45
3.20
0.77
40
3.08
0.30
3.06
0.29
3.03
0.27
3.02
0.28
Zn2+ (1.48)
100
15.27
0.64
14.60
0.29
14.33
0.07
14.07
0.01
80
3.25
1.43
3.31
1.72
3.44
2.99
3.46
3.17
60
2.96
0.75
3.04
0.79
3.13
1.31
3.18
1.66
40
1.44
1.82
1.93
0.008
2.44
0.12
2.82
0.75
aThe values in parenthesis are the ionic sizes in Å [19].
