Tuning Reactivity of Platinum(II) Complexes
Tuning Reactivity of Platinum(II) Complexes Tuning Reactivity of Platinum(II) Complexes
Table of Contents-3 Chapter 3.The π-Acceptor Effect in the Substitution Reactions of Tridentate N- Donor Ligand Complexes of Platinum(II): A Detailed Kinetic and Mechanistic study ................................................................................................................................................................. 1 3.0 Abstract ............................................................................................................................................................... 1 3.1 Introduction ...................................................................................................................................................... 1 3.2 Experimental .................................................................................................................................................... 3 3.2.1 Materials and Procedures ....................................................................................................................... 3 3.2.1.1 Synthesis of the ligands and complexes ....................................................................................... 4 3.2.1.2 Synthesis of [Pt{2–(2’–pyridyl)–1,10–phenanthroline}Cl]Cl ............................................ 4 Synthesis of pyphen ligand ................................................................................................................................ 4 3.2.1.3 Synthesis of Dichloro(1,5-cyclooctadiene) Platinum(II) ..................................................... 6 3.2.1.4 Synthesis of 4’-(2’’’-CH3-phenyl)-6-(3˝-isoquinoyl)-2,2´-bipyridine ligand ...................... 6 3.2.1.5 Synthesis of [Pt{4’–(2’’’–CH3–phenyl)–6–(3’’’–isoquinoyl)–2,2’– bipyridine}Cl]SbF6 ................................................................................................................................................. 8 3.2.1.6 Synthesis of 2,2´:6´,2˝-terpyridine Platinum(II) (PtCl) ......................................................... 9 3.2.1.7 Synthesis of 4’–(2’’’–CH3–phenyl)–2,2’:6’,2’’–terpyridine ligand .................................... 9 3.2.1.8 Synthesis of [Pt{4'–(2"'–CH3-phenyl)–2,2’:6’,2’’–terpyridine}Cl]CF3SO3 (CH3PhPtCl) ............................................................................................................................................................ 10 3.2.2 Physical Measurements and Instrumentation ........................................................................... 11 3.2.3 Computational Modelling .................................................................................................................... 12 3.3 Results ............................................................................................................................................................... 12 3.3.1 Computational Analysis ........................................................................................................................ 12 3.3.2 Kinetic Measurements ........................................................................................................................... 15 3.4 Discussion ....................................................................................................................................................... 20 3.5 Conclusion ....................................................................................................................................................... 24 3.6 References ....................................................................................................................................................... 25 . i
List of figures Figure 3.1 DFT-calculated (B3LYP/LACVP+**) HOMOs and LUMOs for polypyridyl complexes. .............................................................................................................................................................. 13 Figure 3.2: Spectrum obtained from the stopped-flow spectrometer with a single exponential fit for the reaction between CH3PhPtCl (2.50 x10 -5 M) and DMTU (1.25 x 10 -3 M) in methanol followed at 308 nm, I = 0.1 M (LiCF3SO3), T = 298.15 K. ................................ 16 Figure 3.3: Concentration dependence of kobs for the substitution of chloride from pyPhenPtCl (5.0 x 10 -5 M) by (a) thiourea nucleophiles and (b) anionic nucleophiles in methanol, I = 0.1 M (LiCF3SO3), T = 298.15 K. ....................................................................................... 18 Figure 3.4: Plots of ln (k2/T) against 1/T for the substitution of chloride from pyPhenPtCl by TU, DMTU, TMTU, I-, SCN- and Br- in methanol, I = 0.1 M (LiCF3SO3), over the temperature range 288-308 K. ............................................................................................................. 20 Figure 3.5: Absorption spectra of CH3PhPtCl and CH3PhisoqPtCl in acetonitrile ................ 21 List of Tables Table 3.1: Summary of DFT-calculated parameters and numbering system used for the calculation is in the structure shown as an inset. ................................................................................ 14 Table 3.2: Summary of the second-order rate constants at 25 °C and activation parameters for the substitution of chloride from Pt(II) polypyridyl complexes by TU, DMTU, TMTU, and in methanol, I = 0.1 M (LiCF3SO3). ....................................................................... 19 ii
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List <strong>of</strong> figures<br />
Figure 3.1 DFT-calculated (B3LYP/LACVP+**) HOMOs and LUMOs for polypyridyl<br />
complexes. .............................................................................................................................................................. 13<br />
Figure 3.2: Spectrum obtained from the stopped-flow spectrometer with a single<br />
exponential fit for the reaction between CH3PhPtCl (2.50 x10 -5 M) and DMTU (1.25 x 10 -3<br />
M) in methanol followed at 308 nm, I = 0.1 M (LiCF3SO3), T = 298.15 K. ................................ 16<br />
Figure 3.3: Concentration dependence <strong>of</strong> kobs for the substitution <strong>of</strong> chloride from<br />
pyPhenPtCl (5.0 x 10 -5 M) by (a) thiourea nucleophiles and (b) anionic nucleophiles in<br />
methanol, I = 0.1 M (LiCF3SO3), T = 298.15 K. ....................................................................................... 18<br />
Figure 3.4: Plots <strong>of</strong> ln (k2/T) against 1/T for the substitution <strong>of</strong> chloride from<br />
pyPhenPtCl by TU, DMTU, TMTU, I-, SCN- and Br- in methanol, I = 0.1 M (LiCF3SO3), over<br />
the temperature range 288-308 K. ............................................................................................................. 20<br />
Figure 3.5: Absorption spectra <strong>of</strong> CH3PhPtCl and CH3PhisoqPtCl in acetonitrile ................ 21<br />
List <strong>of</strong> Tables<br />
Table 3.1: Summary <strong>of</strong> DFT-calculated parameters and numbering system used for the<br />
calculation is in the structure shown as an inset. ................................................................................ 14<br />
Table 3.2: Summary <strong>of</strong> the second-order rate constants at 25 °C and activation<br />
parameters for the substitution <strong>of</strong> chloride from Pt(<strong>II</strong>) polypyridyl complexes by TU,<br />
DMTU, TMTU, and in methanol, I = 0.1 M (LiCF3SO3). ....................................................................... 19<br />
ii
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