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Tuning Reactivity of Platinum(II) Complexes

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Table <strong>of</strong> Contents-5<br />

Chapter 5 .................................................................................................................................................................... 1<br />

Substitution Reactions in Dinuclear <strong>Platinum</strong>(<strong>II</strong>) <strong>Complexes</strong>: an Evaluation <strong>of</strong> the<br />

influence <strong>of</strong> the diazine-bridge on reactivity ........................................................................................... 1<br />

5.0 Abstract .......................................................................................................................................................... 1<br />

5.1 Introduction ................................................................................................................................................. 2<br />

5.2 Experimental ............................................................................................................................................... 4<br />

5.2.1 Chemical and Solutions ...................................................................................................................... 4<br />

5.2.2 Synthesis <strong>of</strong> the dinuclear Pt(<strong>II</strong>) chloro-complexes (pzn to pht) ................................... 5<br />

5.2.3 Instrumentation and Physical measurements ........................................................................ 6<br />

5.2.4 Computational details ......................................................................................................................... 7<br />

5.2.5 Preparation <strong>of</strong> the aqueous complex solutions ...................................................................... 7<br />

5.2.6 Spectrophotometric pKa titrations ................................................................................................ 8<br />

5.2.7 Kinetic measurements ........................................................................................................................ 8<br />

5.2.8 Properties <strong>of</strong> the Ligands................................................................................................................... 9<br />

5.3 Results ............................................................................................................................................................ 9<br />

5.3.1 Computation calculations .................................................................................................................. 9<br />

5.3.2 Acid dissociation constants (pKa) <strong>of</strong> the diaqua complexes .......................................... 12<br />

5.3.3 NMR study ............................................................................................................................................. 16<br />

5.3.4 Kinetic Measurements with Thiourea nucleophiles .......................................................... 20<br />

5.3.5 Thermodynamic parameters ........................................................................................................ 26<br />

5.4 Discussion .................................................................................................................................................. 29<br />

5.5 Conclusion ................................................................................................................................................. 32<br />

References .............................................................................................................................................................. 33<br />

List <strong>of</strong> Figures<br />

Figure 5.1: Frontier molecular orbitals HOMO –LUMO <strong>of</strong> the complexes ............................... 11<br />

Figure 5.2:Variation <strong>of</strong> absorbance with pH for qzn complex in the pH range 2-10,<br />

I = 0.1 M HClO4, T = 25 °C. Inset: Plot <strong>of</strong> Absorbance versus pH at 305 .0 nm. ................... 13<br />

i

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