Tuning Reactivity of Platinum(II) Complexes

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Table of Contents-2 Chapter Two ........................................................................................................................................................... 1 2.0 Ligand Substitution at Pt(II) Square-planar Centre ...................................................................... 1 2.1 Introduction ................................................................................................................................................. 1 2.2 Mechanism of Ligand Substitution Reactions for Square-planar Complexes .............. 3 2.2.1 The Dissociation Mechanism (D) ................................................................................................... 4 2.2.2 The Associative Mechanism (A)...................................................................................................... 5 2.2.3 The Interchange Mechanism (I) ..................................................................................................... 7 2.3 Measurements of Integrated Rate Constants ................................................................................... 7 2.3.1 Reversible Second-order Reactions .............................................................................................. 7 2.3.2 Activation Parameters ...................................................................................................................... 11 2.3.3 The Arrhenius Theory ...................................................................................................................... 11 2.3.4 The Transition-state Theory ......................................................................................................... 12 2.3.5 Effect of Pressure on Rate Constant .......................................................................................... 14 2.4 Instrumental Techniques Used in Chemical Kinetics ............................................................ 16 2.4.1 Flow Methods ....................................................................................................................................... 18 2.4.2 UV-Visible Spectrophotometry .................................................................................................... 21 2.5 Factors Affecting the Rate of Substitution .................................................................................. 23 2.5.1 Effect of the Entering Group .......................................................................................................... 23 2.5.2 Effect of the Leaving Group ............................................................................................................ 28 2.5.3 Effect of Steric Hindrance ............................................................................................................... 29 2.5.4 Effect of Solvent ................................................................................................................................... 33 2.5.5 Effect of Non-participating Groups ............................................................................................ 35 2.5.5.1 cis-and trans-Effects of Platinum(II) Complexes ............................................................. 35 2.5.2.2 The Trans-effect ............................................................................................................................... 35 References .............................................................................................................................................................. 40 i
List of Figures Figure 2.1: Structures of some monofunctional platinum(II) complexes active against human colon carcinoma cell line (HCT-116). 11 ................................................................................. 2 Figure 2.2: Potential energy profiles of different mechanisms occurring at a square planar Pt(II) centre as proposed by Langford-Gray. 5 .............................................................................................. 4 Figure 2.3: Typical plots of the pseudo first-order rate constants, kobs versus. the concentration of the entering nucleophiles for the substitution reaction of a dinuclear Pt(II) complex at 298 K in aqueous solution. .............................................................................................................. 10 Figure 2.4: Summary of reaction techniques and their associated time scales available for the monitoring chemical kinetics. 28 ........................................................................................................... 17 Figure 2.5: A schematic diagram of a continuous flow kinetic system. d = distance from the mixer to the point of observation. ................................................................................................ 19 Figure 2.6: Schematic diagram of a stopped flow apparatus. 13 ............................................... 20 Figure 2.7: Kinetic trace at 448 nm for the substitution reaction between CH3PhisoqPtCl (0.054 mM) and I - (6.06 mM) at 298 K, I = 0.1 M Li(SO3CF3) in methanol. .......................................... 20 Figure 2.8: A schematic diagram of a UV-Visible Spectrophotometry set-up. .......................................... 21 Figure 2.9: Rates of Pt(II) complexes correlated with trans-[Pt(py)2Cl2] as reference, for different entering nucleophiles: • = trans-[Pt(PEt3)2Cl2] in methanol at 30 °C; ▲ = [Pt(en)Cl2] in water at 35 °C. 18............................................................................................................................. 27 Figure 2.10: The steric effect on the trigonal bipyramidal intermediate of the cis isomer in comparison to trans-isomer. 36 ............................................................................................ 32 Figure 2.11: Geometry of an aryl square-planar complex showing the ortho- substituents block the site of attack. 6,26,37 ........................................................................................................ 32 Figure 2.12: (a) σ-donation from the filled ligand px orbital to vacant metal 5dx 2 -y 2 orbital. (b) πback-donation from the filled metal dxz orbital to the antibonding linear combination of carbons’ px orbitals in C2H4. 51 .......................................................................................................... 37 ii
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Tuning Reactivity of Platinum(II) C
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Declaration This thesis report is b
Page 5 and 6:
Abstract Systematic kinetic and the
Page 7 and 8: Table of contents Acknowledgements
Page 9 and 10: 2.5.5 Effect of Non-participating G
Page 11 and 12: 5.2.1 Chemical and Solutions ......
Page 13 and 14: 7.2 Experimental Section ..........
Page 15 and 16: procurements, Messers P. Forder and
Page 17 and 18: Figure 2.2 Potential energy profile
Page 19 and 20: Figure 4.6 Concentration dependence
Page 21 and 22: Figure 6.1 Spectrophotometric titra
Page 23 and 24: List of Tables Table 2.1 A selectio
Page 25 and 26: Table 6.4 Summary of rate constants
Page 27 and 28: TU thiourea DMTU 1,3-dimethyl-2-thi
Page 30 and 31: Table of Contents-1 Chapter 1 .....
Page 32 and 33: 1.0 Introduction 1.1 Cancer Disease
Page 34 and 35: toxic potential. The most well-know
Page 36 and 37: 1.3.2.2 Cellular Uptake Cisplatin i
Page 38 and 39: H 3N OH 2 Pt H 3N OH 2 Active Pt(II
Page 40 and 41: transformational pathways that comp
Page 42 and 43: the hydrolysis of the complex, wher
Page 44 and 45: 1.3.4 Terpyridine Platinum(II) Comp
Page 46 and 47: H 3 N Cl Pt NH 3 H 3 N NH 2 (CH 2 )
Page 48 and 49: 1.4 Kinetic Interest The platinum-b
Page 50 and 51: 3. The effect of varying the positi
Page 52 and 53: 17 R. A. Henderson, The Mechanism o
Page 54 and 55: Altona J. H. van Boom, G. A. van de
Page 56 and 57: 76 (a)J. Kašpárková, J. Zehnulov
Page 60 and 61: List of Tables Table 2.1: A selecti
Page 62 and 63: The mononuclear Pt(II) complexes 1-
Page 64 and 65: Potential Energy R + X RX 1 transit
Page 66 and 67: For the associative mechanism (A),
Page 68 and 69: the concentration of one of the rea
Page 70 and 71: k obs , s -1 0.00030 0.00025 0.0002
Page 72 and 73: k = Ae -Ea/RT 2.14 lnk = lnA - E a
Page 74 and 75: = 23.76 + R Hence, a plot of ln ⎛
Page 76 and 77: iii. # Δ V ≈ 10 cm3 mol-1 featur
Page 78 and 79: conventional methods are classical
Page 80 and 81: Figure 2.6: Schematic diagram of a
Page 82 and 83: The light transmitted from the samp
Page 84 and 85: c. Oxidizability: Ligands that are
Page 86 and 87: Table 2.1: A selection of n o pt va
Page 88 and 89: eaction with different nucleophiles
Page 90 and 91: eaction site from direct attack by
Page 92 and 93: PEt 3 PEt 3 R PEt 3 Pt Pt Y Y Cl R
Page 94 and 95: direct displacement of the leaving
Page 96 and 97: therefore, weaken the bond of the l
Page 98 and 99: σ-Donation According to classical
Page 100 and 101: References 1 (a) J. Reedijk, Chem.
Page 102 and 103: 34 R. B. Jordan, Reaction Mechanism
Page 104 and 105: Table of Contents-3 Chapter 3.The
Page 106 and 107: Chapter 3 The π-Acceptor Effect in
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In order to extend our understandin
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after which water was added to quen
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O CH 3 + I + N O oH - N O O 7 CH 3
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84% (34.7 mg, 0.0618 mmol). 1 H NMR
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PhCN PhCN Pt Cl Cl + N N CH 3 N CH
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Complex Structure HOMO LUMO PtCl CH
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The geometry-optimised structures i
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against the concentration of the in
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Table 3.2: Summary of the second-or
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constants of CH3PhisoqPtCl decrease
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with π*-orbitals of the ligand. Th
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3.6 References 1 D. Rosenberg, L. V
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30 Microcal TM Origin TM Version 5.
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Figure S3.1: Kinetic trace at 448 n
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ln(k 2 /T) -6.0 -7.5 -9.0 -10.5 -12
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Table S3.3b: Average observed rate
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Table S3.5b: Temperature dependence
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Table S3.8: DFT calculated electros
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List of Figures Figure 4.1: Structu
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Table 4.2: Summary of pKa values fo
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4.1 Introduction Platinum compounds
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cis geometry, leading to dramatic c
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ligand was added to the [{cis-PtCl(
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spectra were measured in and refere
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4.3.1 DFT calculated Optimized Stru
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Table 4.1: A summary of the DFT cal
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H2O-Pt-L-Pt-OH2 H2O-Pt-L-Pt-OH2 H2O
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electrophilicity and acidity of the
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(A) 18 Absorbance 0.08 0.07 0.06 0.
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k obs(3 rd ) , s -1 -5 6.00x10 TMTU
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4.3.4 Kinetics with NMR The substit
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ln([ML] t ) 4.0 3.5 3.0 2.5 2.0 1.5
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ln(k 2(1 st ) /T) -3.5 -4.0 -4.5 -5
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Comple x Table 4.4: Summary of Acti
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The decrease in reactivity of 2,6pz
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Table 4.5: DFT calculated (NBO) cha
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eaction proceeds via bimolecular pa
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References 1 T. Storr, K. H.Thomson
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36 D. Jaganyi, D. Reddy, J.A. Gerte
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Appendix 4 THE INFLUENCE OF THE PYR
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Absorbance at 368. 0 nm 0. 0 8 0. 0
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Table S4.3: Average observed rate c
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k nd obs(2 ) , s-1 0.003 TU DMTU TM
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k obs2 , s -1 2.40x10 -4 2.20x10 -4
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Table S4.13: Average observed rate
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k obs(1 st ) , s -1 0.06 0.04 0.02
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ln(k 2(3 rd ) /T) -10.0 -10.5 -11.0
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SpinWorks 2.5: 2,6 pznClO4 in D2O N
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Table of Contents-5 Chapter 5 .....
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List of Tables Table 5.1: A summary
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5.1 Introduction Multinuclear plati
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onding. For this reason, pKa titrat
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400-300 cm -1): 3308, 3117, 3071 (N
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5.2.6 Spectrophotometric pKa Titrat
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Table 5.1: A summary of DFT-calcula
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However, because the highest occupi
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Table 5.2: Acid dissociation consta
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Table 5.3: A summary of DFT calcula
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H3N 6 eq TU 0 eq TU Ha NH3 Ha Cl TU
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third step due to the trans-effect
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[H 2 O-Pt-(NN)-Pt-OH 2 ] +4 [NU-Pt-
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k obs(1st) / s -1 0.20 TU DMTU TMTU
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thiourea nucleophile is large enoug
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ln(k st 2(1 ) /T) -3 -4 -5 -6 -7 -8
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is the same as the electron-withdra
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associative mode of substitution me
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16 H. Ertürk, J. Maigut, R. Puchta
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43 (a) D. Jaganyi, A. Hofmann and R
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276 nm Absorbance 0 . 6 5 0 . 6 4 0
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k obs(1 st ) , s -1 0.4 0.3 0.2 0.1
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ln(k 2(2 nd ) /T) -8.0 TU -8.5 -9.0
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pzn PPM -1750.0 -1850.0 -1950.0 -20
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Figure S5.13: UV/Visible spectra fo
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k obs(1 st ) in s -1 0.030 0.025 0.
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ln(k 2(2 nd ) /T) -10 -11 -12 -13 -
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9.61 ppm Ha PPM 9.8 9.6 9.4 9.2 9.0
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k obs(3rd) / s -1 -5 8 .00 x 10 T U
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ln(k st 2(1 ) /T) -1.5 TU DMTU TMTU
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ln(k rd 2(3 ) /T) -8.5 -9.0 -9.5 -1
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SpinWorks 2.5: znPt(II)-OP4 in D2O
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Figure S5.31: Mass spectrum for com
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ln(k st 2(1 ) /T) -4 -5 -6 -7 -8 -9
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SpinWorks 2.5: phtPt(II)-OP2 in D2O
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Figure S5.41: Mass spectrum for com
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List of Figures Figure 6.1: Spectro
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Chapter 6 Tuning Reactivity of Plat
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Against this background, several re
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6.2.2 Instruments Microanalyses wer
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Metal Complex Pt3 Yield: 52.5 mg (0
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6.3 Results 6.3.1 Synthesis and Cha
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The pKa values obtained are summari
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Table 6.2: DFT-calculated parameter
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that of dinuclear Pt(II) complexes
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It can be concluded that substituti
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ate constants, kobs(1 st /2 nd ), w
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Table 6.3: Summary of rate constant
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6.3.6 Activation Parameters The act
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pKa1 values become smaller. In addi
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of steric influence is felt by the
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6.5 Conclusion The present study ha
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17 O. F. Wendt and L. I. Elding, 19
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51 Y. Iwadata, K. Kawamura, K. Igar
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Table S6.4(b): Average observed rat
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ln(k 2(2 nd ) /T) -4 -6 -8 -10 -12
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45.0 40 35 30 25 20 %T 15 10 5 0 -5
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k st obs(1 ) in s-1 0.30 Br TU 0.25
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-2304.16 ppm H 3N PPM -2200.0 -2220
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Absorbance 1.6 1.4 1.2 1.0 0.8 0.6
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SH N SH + Mechanism Br N + CO 3 2-
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Figure 7.5: 195Pt NMR spectra of mi
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linker remained coordinated to the
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complexes, have a lower charge and
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ange 326-400 cm -1 (weak) for Pt-Cl
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ButPt, HexPt, OctPt and DecPt, were
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7.3 Results 7.3.1 DFT Calculations
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Structure HOMO LUMO EnPt (C2h) Prop
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Absorbance Table 7.2: Summary of pK
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coordination to the soft Pt(II) cen
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observed at -2962.4 and -3024.1 ppm
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H 3N NH 3 Pt NH 2 OH 2 n NH 3 NH 2
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k obs2 , in s -1 -3 TU 1.2x10 DMTU
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7.3.4 Activation Parameters The tem
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density is located on the metal cen
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acetylmethionine, which reported th
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References 1 (a) B. Rosenberg, L. V
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32 N. Summa, J. Maigut, R. Puchta a
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Appendix 7 Table S7.1: Summary of s
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k obs(2 nd ) , in s -1 0.00020 0.00
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ln(k 2(2 nd ) /T) -8.5 -9.0 -9.5 -1
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k obs(1 st ) , in s -1 0.06 TU DMTU
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ln(k 2(1 st ) /T) -3.2 TU DMTU TMTU
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Table S7.11: Summary of kobs(2 nd )
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%T 22.0 20 18 16 14 12 10 8 6 4 2 0
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k st obs(1 ) , in s-1 0.10 0.08 0.0
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ln(k st 2(1 ) /T) -4.0 TU DMTU TMTU
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Figure S7.23: Mass spectra for HexP
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Table S21: Average observed rate co
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Table S7.23: Summary of kobs(2 nd )
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90.0 80 70 60 50 40 30 20 %T 10 0 -
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Figure S7.37: Mass spectrum for Hex
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Chapter 8 Tuning Reactivity of plat
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dinuclear Pt(II) complexes to relea
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finally Pt2. The order of reactivit
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• prolonged survival in the cell
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Tuning Reactivity of Platinum(II) Complexes

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