Tuning Reactivity of Platinum(II) Complexes
Tuning Reactivity of Platinum(II) Complexes Tuning Reactivity of Platinum(II) Complexes
(A) 18 Absorbance 0.08 0.07 0.06 0.05 0.04 (i) 0.03 0 10 20 30 40 250 500 750 1000 1250 1500 1750 (ii) Time, min Figure 4.4: Typical three well-separated kinetic traces for the three steps reaction between pzn (2.14 x 10 -5 M) and TU (1.00 x 10 -3 M) monitored at 395 nm, T= 298.15 K, pH = 2.0, I = 0.1 M NaClO4, adjusted with 0.01 M HClO4. Step (A): the substitution of the first aqua ligand by stopped-flow technique. Step (B): (i) the substitution of the second aqua ligand and (II) the dissociation of the diazine linker and substitution of ancillary ligands in the third step studied by UV-Vis Spectrophotometric technique. The observed pseudo first-order rate constant values (kobs 1/2/3) of each step were found to vary linearly with the concentration of the nucleophiles. The plots of kobs versus nucleophile concentrations were found to be linear, passing through the origin with positive slopes as shown in Figures 4.5, 4.6 and 4.7, for the 2,5pzn complex (also Figures.S4.5-S4.7, S4.11–S4.13 and S4.17–S4.19 for the corresponding complexes pzn, 2,6pzn and 2,3pzn, appendix). (B)
k st obs(1 ) , s-1 0.04 0.03 0.02 0.01 TU DMTU TMTU 0.00 0.000 0.002 0.004 0.006 0.008 [NU]/ mol dm -3 Figure 4.5: Concentration dependence of kobs(1 st ) for the substitution of k obs(2 nd ) , s -1 first aqua ligand in 2,5pzn by thiourea nucleophiles, pH = 2.0, T = 298.15 K, I = 0.10 M (0.01 M HClO4, adjusted with NaClO4). 0.003 TU DMTU TMTU 0.002 0.001 0.000 0.00 0.02 0.04 0.06 0.08 0.10 [NU]/ mol dm -3 Figure 4.6: Concentration dependence of kobs(2 nd ) for the substitution of second aqua ligand in 2,5pzn by thiourea nucleophiles, pH = 2.0, T = 298.15 K, I = 0.10 M (0.01 M HClO4, adjusted with NaClO4). 19
- Page 114 and 115: 84% (34.7 mg, 0.0618 mmol). 1 H NMR
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(A)<br />
18<br />
Absorbance<br />
0.08<br />
0.07<br />
0.06<br />
0.05<br />
0.04<br />
(i)<br />
0.03<br />
0 10 20 30 40 250 500 750 1000 1250 1500 1750<br />
(ii)<br />
Time, min<br />
Figure 4.4: Typical three well-separated kinetic traces for the three steps reaction<br />
between pzn (2.14 x 10 -5 M) and TU (1.00 x 10 -3 M) monitored at 395 nm,<br />
T= 298.15 K, pH = 2.0, I = 0.1 M NaClO4, adjusted with 0.01 M HClO4. Step<br />
(A): the substitution <strong>of</strong> the first aqua ligand by stopped-flow technique.<br />
Step (B): (i) the substitution <strong>of</strong> the second aqua ligand and (<strong>II</strong>) the<br />
dissociation <strong>of</strong> the diazine linker and substitution <strong>of</strong> ancillary ligands in<br />
the third step studied by UV-Vis Spectrophotometric technique.<br />
The observed pseudo first-order rate constant values (kobs 1/2/3) <strong>of</strong> each step were found<br />
to vary linearly with the concentration <strong>of</strong> the nucleophiles. The plots <strong>of</strong> kobs versus<br />
nucleophile concentrations were found to be linear, passing through the origin with<br />
positive slopes as shown in Figures 4.5, 4.6 and 4.7, for the 2,5pzn complex (also<br />
Figures.S4.5-S4.7, S4.11–S4.13 and S4.17–S4.19 for the corresponding complexes pzn,<br />
2,6pzn and 2,3pzn, appendix).<br />
(B)
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