Tuning Reactivity of Platinum(II) Complexes

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List of Tables Table 5.1: A summary of DFT-calculated parameters for the aqua complexes pzn to pht. The table is ordered according to increasing values of Natural Atomic charges (NBO) of Pt(II) centres. ........................................................................................................................................................ 10 Table 5.2 : Acid dissociation constants of platinum(II) complexes determined spectrophotometrically at 25 °C (Ionic strength, I = 0.1 M NaClO4/ HClO4). ....................... 14 Table 5.3: A summary of DFT calculated Parameters for aqua/hydroxo complex systems of benzodiazines and their monocyclic analogues. ............................................................................ 16 Table 5.4: Summary of second order rate constants of diazine-bridged dinuclear Pt(II) complexes; I = 0.1 M (NaClO4, adjusted with HClO4), T = 298.15 K. ........................................... 23 Table 5.5: Summary of Activation parameters for the displacement of coordinated water by a series of nucleophiles in complexes of the Type [cis-{PtOH2(NH3)2-μ-pzn] 4+, I = 0.1 M NaClO4. ................................................................................................................................................................ 27 iii
Chapter 5 Substitution Reactions in Dinuclear Platinum(II) Complexes: an Evaluation of the Influence of the Diazine-bridge on Reactivity 5.0 Abstract The kinetics of substitution reactions of aqua dinuclear Pt(II) complexes, [{cis– Pt(OH2)(NH3)2}2–μ–pmn](ClO4)2 (pmn), [{cis–Pt(OH2)(NH3)2}2–μ–pdn](ClO4)2 (pdn), [{cis–Pt(OH2)(NH3)2}2–μ–qzn](ClO4)2 (qzn), [{cis–Pt(OH2)(NH3)2}2–μ– pht](ClO4)2 (pht), and [{cis–Pt(OH2)(NH3)2}2–μ–pzn](ClO4)2 (pzn) (pmn = pyrimidine, pdn = pyridazine, qzn = quinazoline, pht = phthalazine, pzn = pyrazine) and sulphur-donor nucleophiles, viz. thiourea (TU), N,N–dimethylthiourea (DMTU) and N,N,N,N–tetramethylthiourea (TMTU) were investigated. The reactions were followed under pseudo first-order conditions as a function of nucleophile concentration and temperature using stopped-flow and UV-Vis Spectrophotometric methods. The reactivity of the nucleophiles follows the order TU > DMTU > TMTU. The results of the rate constants for the consecutive substitution of the aqua ligand showed that pzn is more reactive than the rest of dinuclear complexes. The reactivity of the aqua complexes follows the order pzn > qzn > pmn > pdn > pht which was confirmed by the quantum chemical (DFT) NBO charges and the pKa calculations. The results indicate that changing the position or distance of the N atoms of the bridging ligand controls the electrophilicity of the metal centre and hence its reactivity. The results further indicate that the metal centre is activated differently in the cases of qzn and pht, even though both are part of a π–conjugated system. The negative values reported for the activation entropy confirm the associative nature of substitution process. 1H NMR was used to follow the substitution of the aqua ligand by excess thiourea and confirmed the displacement of the bridging ligand in the third step in all cases. The results clearly demonstrate a strong connection between the reactivity of the dinuclear Pt(II) complexes with sulphur nucleophiles and their structural and electronic characteristics. 1
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Tuning Reactivity of Platinum(II) C
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Declaration This thesis report is b
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Abstract Systematic kinetic and the
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Table of contents Acknowledgements
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2.5.5 Effect of Non-participating G
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5.2.1 Chemical and Solutions ......
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7.2 Experimental Section ..........
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procurements, Messers P. Forder and
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Figure 2.2 Potential energy profile
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Figure 4.6 Concentration dependence
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Figure 6.1 Spectrophotometric titra
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List of Tables Table 2.1 A selectio
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Table 6.4 Summary of rate constants
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TU thiourea DMTU 1,3-dimethyl-2-thi
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Table of Contents-1 Chapter 1 .....
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1.0 Introduction 1.1 Cancer Disease
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toxic potential. The most well-know
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1.3.2.2 Cellular Uptake Cisplatin i
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H 3N OH 2 Pt H 3N OH 2 Active Pt(II
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transformational pathways that comp
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the hydrolysis of the complex, wher
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1.3.4 Terpyridine Platinum(II) Comp
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H 3 N Cl Pt NH 3 H 3 N NH 2 (CH 2 )
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1.4 Kinetic Interest The platinum-b
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3. The effect of varying the positi
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17 R. A. Henderson, The Mechanism o
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Altona J. H. van Boom, G. A. van de
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76 (a)J. Kašpárková, J. Zehnulov
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Table of Contents-2 Chapter Two ...
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List of Tables Table 2.1: A selecti
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The mononuclear Pt(II) complexes 1-
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Potential Energy R + X RX 1 transit
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For the associative mechanism (A),
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the concentration of one of the rea
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k obs , s -1 0.00030 0.00025 0.0002
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k = Ae -Ea/RT 2.14 lnk = lnA - E a
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= 23.76 + R Hence, a plot of ln ⎛
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iii. # Δ V ≈ 10 cm3 mol-1 featur
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conventional methods are classical
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Figure 2.6: Schematic diagram of a
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The light transmitted from the samp
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c. Oxidizability: Ligands that are
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Table 2.1: A selection of n o pt va
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eaction with different nucleophiles
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eaction site from direct attack by
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PEt 3 PEt 3 R PEt 3 Pt Pt Y Y Cl R
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direct displacement of the leaving
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therefore, weaken the bond of the l
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σ-Donation According to classical
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References 1 (a) J. Reedijk, Chem.
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34 R. B. Jordan, Reaction Mechanism
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Table of Contents-3 Chapter 3.The
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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.
Page 166 and 167: k obs(3 rd ) , s -1 -5 6.00x10 TMTU
Page 168 and 169: 4.3.4 Kinetics with NMR The substit
Page 170 and 171: ln([ML] t ) 4.0 3.5 3.0 2.5 2.0 1.5
Page 172 and 173: ln(k 2(1 st ) /T) -3.5 -4.0 -4.5 -5
Page 174 and 175: Comple x Table 4.4: Summary of Acti
Page 176 and 177: The decrease in reactivity of 2,6pz
Page 178 and 179: Table 4.5: DFT calculated (NBO) cha
Page 180 and 181: eaction proceeds via bimolecular pa
Page 182 and 183: References 1 T. Storr, K. H.Thomson
Page 184 and 185: 36 D. Jaganyi, D. Reddy, J.A. Gerte
Page 186 and 187: Appendix 4 THE INFLUENCE OF THE PYR
Page 188 and 189: Absorbance at 368. 0 nm 0. 0 8 0. 0
Page 190 and 191: Table S4.3: Average observed rate c
Page 192 and 193: k nd obs(2 ) , s-1 0.003 TU DMTU TM
Page 198 and 199: k obs2 , s -1 2.40x10 -4 2.20x10 -4
Page 200 and 201: Table S4.13: Average observed rate
Page 206 and 207: k obs(1 st ) , s -1 0.06 0.04 0.02
Page 210 and 211: ln(k 2(3 rd ) /T) -10.0 -10.5 -11.0
Page 212 and 213: SpinWorks 2.5: 2,6 pznClO4 in D2O N
Page 214 and 215: Table of Contents-5 Chapter 5 .....
Page 218 and 219: 5.1 Introduction Multinuclear plati
Page 220 and 221: onding. For this reason, pKa titrat
Page 222 and 223: 400-300 cm -1): 3308, 3117, 3071 (N
Page 224 and 225: 5.2.6 Spectrophotometric pKa Titrat
Page 226 and 227: Table 5.1: A summary of DFT-calcula
Page 228 and 229: However, because the highest occupi
Page 230 and 231: Table 5.2: Acid dissociation consta
Page 232 and 233: Table 5.3: A summary of DFT calcula
Page 234 and 235: H3N 6 eq TU 0 eq TU Ha NH3 Ha Cl TU
Page 236 and 237: third step due to the trans-effect
Page 238 and 239: [H 2 O-Pt-(NN)-Pt-OH 2 ] +4 [NU-Pt-
Page 240 and 241: k obs(1st) / s -1 0.20 TU DMTU TMTU
Page 242 and 243: thiourea nucleophile is large enoug
Page 244 and 245: ln(k st 2(1 ) /T) -3 -4 -5 -6 -7 -8
Page 246 and 247: is the same as the electron-withdra
Page 248 and 249: associative mode of substitution me
Page 250 and 251: 16 H. Ertürk, J. Maigut, R. Puchta
Page 252 and 253: 43 (a) D. Jaganyi, A. Hofmann and R
Page 254 and 255: 276 nm Absorbance 0 . 6 5 0 . 6 4 0
Page 256 and 257: k obs(1 st ) , s -1 0.4 0.3 0.2 0.1
Page 260 and 261: ln(k 2(2 nd ) /T) -8.0 TU -8.5 -9.0
Page 262 and 263: 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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Table S5.17: Average observed rate
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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 S6.3: Average observed rate c
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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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Table S6.9: Average observed rate c
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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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