%40تخفیف

ORGANOPLATINUM CYCLOMETALATED COMPLEXES CONTAINING 1-PHENYLPYRAZOLATE

تعداد100صفحه در فایل word

M.Sc. THESIS IN

INORGANIC CHEMISTRY

ORGANOPLATINUM CYCLOMETALATED COMPLEXES CONTAINING

1-PHENYLPYRAZOLATE

Mononuclear cyclometalated complex [PtMe(ppz-H)(DMSO)], in which ppz-H = 1-phenylpyrazole, was used as a precursor complex and treated with the phosphine ligand PPh₃. The product was reacted with MeI to give a Pt(IV) complex [PtMe₂I(ppz-H)(PPh₃)]. The complexes were characterized by ¹H and ³¹P NMR, specteroscopy and elemental analysis. Besides, kinetic of the oxidative addition reaction of the new complex [PtMe(ppz-H)(PPh₃)] with MeI was studied using UV-vis spectroscopy. On the basis of kinetic studies, it was suggested that the latter oxidative addition reaction was proceeded by an S_N2 mechanism. The rates of the reaction at different temperatures were measured and consistent with the proposed mechanism, a large negative ∆S^‡value was found. Also, this mechanism was theoretically investigated using DFT calculations and the geometry of transition state and energy barriers were determined.

Key words: Cyclometalation, Oxidative addition, Kinetic, DFT calculations

دسته: زبان خارجه, زبان خارجه برچسب: DFT calculations, Key words: Cyclometalation, Kinetic, Oxidative addition

توضیحات

Table of Contents

Content Page

CHAPTER ONE: INTRODUCTION AND LITERATURE REVIEW

1.1. General introduction. 2

1.2. Metal Alkyl Complexes. 3

1.2.1. Structure and Bonding. 3

1.3. Organometallic Chemistry. 4

1.4. Organoplatinum Complexes. 5

1.4.1. Bonding. 6

1.4.2. Stability. 7

1.5. Phosphorus Ligands. 9

1.5.1. Structure and Bonding. 11

1.5.2. Steric Effects of Phosphorus Ligands. 12

1.5.3. Ligand Cone Angles. 12

1.6. Cyclometalation Reactions. 13

1.7. Cyclometalation of the Platinum Metals with Nitrogen. 16

1.8. Oxidative Addition Reaction of Organoplatinum Complexes. 17

1.9. Objective. 19

CHAPTER TWO: EXPERIMENTAL

2.1. General Remarks. 21

2.2. The Source of Chemicals. 21

2.3. Techniques and Methods. 21

2.3.1. Inert Atmosphere Techniques. 21

2.3.2.¹H NMR Spectroscopy. 22

2.3.3.³¹P{¹H} NMR Spectroscopy. 22

2.3.4. UV-vis Spectroscopy. 22

2.3.5. Microanalysis. 22

Content Page

2.3.6. Determination of Melting Points. 23

2.4. Preparative Works. 23

2.4.1. Preparation of Dry Ether 23

2.5. Preparation of Starting Compounds. 23

2.5.1. Preparation of K₂PtCl₆ from Laboratory Platinum Residual 23

2.5.2. Preparation of K₂PtCl₄ 24

2.5.3. Preparation of cis/trans-[PtCl₂(SMe₂)₂] 24

2.5.4. Preparation of [Me₂Pt(m-SMe₂)₂PtMe₂] 25

2.5.5. Preparation of [PtMe₂(DMSO)₂] 25

2.5.6. Preparation of [PtMe(ppz-H)(DMSO)] 26

2.5.7. Preparation of [PtMe(ppz-H)(PPh₃)] 26

2.5.8. Preparation of [PtMe₂I(ppz-H)(PPh₃)] 27

2.6. DFT-Computed Geometries. 27

2.7. Kinetic Investigations. 28

2.8. X-Ray Structure Determinations. 28

CHAPTER THREE: RESULTS AND DISCUSSION

3.1. General Consideration about NMR Spectroscopy. 32

3.1.1.¹H NMR Spectra. 32

3.1.2.³¹P{¹H} NMR Spectra. 34

3.2. Synthesis and Characterization of Starting Compounds. 36

3.2.1. cis/trans-[PtCl₂(SMe₂)₂] 36

3.2.1.1.¹H NMR of cis/trans-[PtCl₂(SMe₂)₂] 36

3.2.2. [Me₂Pt(m-SMe₂)₂PtMe₂] 38

3.2.2.1.¹H NMR of [Me₂Pt(m-SMe₂)₂PtMe₂] 38

3.2.3. [PtMe₂(DMSO)₂] 40

3.2.4. [PtMe(ppz-H)(DMSO)] 42

3.2.4.1. Elemental Analysis of [PtMe(ppz-H)(DMSO)] 42

3.2.4.2.¹H NMR Spectrum of [PtMe(ppz-H)(DMSO)] 42

3.2.5. [PtMe(ppz-H)(PPh₃)] 46

Content Page

3.2.5.1. Elemental Analysis of [PtMe(ppz-H)(PPh₃)] 46

3.2.5.2.¹H NMR Spectrum of [PtMe(ppz-H)(PPh₃)] 46

3.2.5.3.³¹P{¹H} NMR Spectrum of [PtMe(ppz-H)(PPh₃)] 48

3.2.5.4. X-Ray Crystal Structure Determination of [PtMe(ppz-H)(PPh₃)] 48

3.2.6. [PtMe₂I(ppz-H)(PPh₃)] 50

3.2.6.1. Elemental Analysis of [PtMe₂I(ppz-H)(PPh₃)] 50

3.2.6.2.¹H NMR Spectrum of [PtMe₂I(ppz-H)(PPh₃)] 51

3.2.6.3.³¹P{¹H} NMR Spectrum of [PtMe₂I(ppz-H)(PPh₃)] 53

3.2.6.4. X-Ray Crystal Structure Determination of [PtMe₂I(ppz-H) (PPh₃)] 53

3.3. Kinetic and Mechanitic Study of Reaction of [PtMe(ppz-H)(PPh₃)] with MeI 56

3.4. Suggested Mechanism.. 59

3.5. Computational Details. 60

3.5.1. Mechanistic Investigation of the Oxidative Addition Reaction. 60

3.5.2. Population Charge. 66

3.5.3. Frontier Molecular Orbitals. 66

3.6. Conclusions. 71

REFERENCES. 72

APPENDIX.. 75

Abstract and Title Page in Persian

List of Tables

Table Page

Table ‎2.1. Crystal data and structure refinement for [PtMe(ppz-H)(PPh₃)] 29

Table ‎2.2. Crystal data and structure refinement for [PtMe₂I(ppz-H)(PPh₃)] 30

Table ‎3.1. Elemental analysis of [PtMe(ppz-H)(DMSO)] 42

Table ‎3.2. Elemental analysis of [PtMe(ppz-H)(PPh₃)] 46

Table ‎3.3. Bond lengths [Å] and angles [º] for [PtMe(ppz-H)(PPh₃)] 49

Table ‎3.4. Elemental Analysis of [PtMe₂I(ppz-H)(PPh₃)] 50

Table ‎3.5. Bond lengths [Å] and angles [º] for [PtMe₂I(ppz-H)(PPh₃)] 55

Table ‎3.6. Second-order rate constants (estimated errors in k values are ± 5%)

and activation parameters for the reaction of the [PtMe(ppz-H) (PPh₃)] with MeI 59

Table ‎3.7. Computed activation parameters and reaction thermodynamics (free energies and enthalpies in kJmol^-1; entropies in JK^-1mol^-1) for oxidative addition of MeI to [PtMe(ppz-H)(PPh₃)] in CHCl₃ solvent…………………………………………………………………………………………. 65

Table ‎3.8. APT charges of R to Pʹ 66

Table ‎3.9. Energies (eV) and main compositions (%) of the relevant frontier orbitals of species involved in the reaction of R with MeI. 70

List of Figures

Figure Page

Figure ‎1.1. Orbital interaction in metal-alkyl bond. 3

Figure ‎1.2. Bridging alkyl in Al₂Me₆ 4

Figure ‎1.3. Syn– and anti– forms of trans-[Pt (PEt₃)₂(o-MeC₆H₄)₂], (PEt₃ groups lie above and below of the plane of paper) 9

Figure ‎1.4. Some typical phosphine ligands. 10

Figure ‎1.5. Shading represents orbital occupation. 11

Figure ‎1.6. Tolman’s cone angle. 12

Figure ‎1.7. Some examples of ortho-metalation complexes. 14

Figure ‎1.8. Benzo-fused heterocycles ligands. 15

Figure ‎3.1. ¹H NMR patterns for SMe₂ protons (a) bridging SMe₂ and (b) terminal SMe₂ 34

Figure ‎3.2. Square planar complex [MH(PPh₃)₃] 35

Figure ‎3.3. ³¹P NMR Spectrum of the square planar complex [MH(PPh₃)₃] (Note that we don’t see any coupling between P and H in this spectrum because it has been removed by the decoupler, all the coupling is P-P coupling.) 35

Figure ‎3.4. ¹H NMR Spectrum (250 MHz) of a mixture of trans/cis– [PtCl₂(SMe₂)₂] in CDCl₃. The inset shows the SMe₂ region. 37

Figure ‎3.5. ¹H NMR Spectrum (250 MHz) of [Pt₂(Me)₄(µ-SMe₂)₂] in CDCl₃ 39

Figure ‎3.6. ¹H NMR Spectrum (250 MHz) of [PtMe₂(DMSO)₂], in CDCl₃ 41

Figure ‎3.7 (a). ¹H NMR Spectrum (250 MHz) of [PtMe(ppz-H)(DMSO)] in CDCl₃ 44

Figure ‎3.8. ¹H NMR Spectrum (250 MHz) of [PtMe(ppz-H)(PPh₃)], in CDCl₃ 47

Figure ‎3.9. ³¹P{¹H} NMR Spectrum (202.4 MHz) of [PtMe(ppz-H)(PPh₃)] in CDCl₃ 48

Figure ‎3.10. The crystal structure of complex [PtMe(ppz-H)(PPh₃)] 49

Figure Page

Figure ‎3.11. ¹H NMR Spectrum (250 MHz) of [PtMe₂I(ppz-H)(PPh₃)] in CDCl₃ ..52

Figure ‎3.12. ³¹P{¹H} NMR Spectrum (202.4 MHz) of [PtMe₂I(ppz-H)(PPh₃)] in CDCl₃ 53

Figure ‎3.13. The crystal structure of complex [PtMe₂I(ppz-H)(PPh₃)] 54

Figure ‎3.14. Changes in the UV-visible spectrum during the reaction of complex [PtMe(ppz-H)(PPh₃)], (3×10^-4 M) with MeI in CHCl₃ at T = 25°C, (a) initial spectrum (before adding MeI), (b) after adding MeI. 56

Figure ‎3.15. Absorbance-time curves for the reaction of complex [PtMe(ppz-H) (PPh₃)], with MeI in CHCl₃ at 25 ˚C 57

Figure ‎3.16. Plots of first-order rate constants (k_obs /s^-1) for the reaction of [PtMe(ppz-H)(PPh₃)] with MeI in CHCl₃ at different temperatures (15 °C; 25 °C; 30 °C; 35 °C; 40 °C) versus the concentration of MeI 58

Figure ‎3.17. Eyring plot for the reaction of complex [PtMe(ppz-H)(PPh₃)] with MeI in CHCl₃ 58

Figure ‎3.18. Structural changes (bond distances in Å) in oxidative addition of MeI to the square planar [PtMe(ppz-H)PPh₃] complex, R, and the optimized geometries in CHCl₃ 63

Figure ‎3.19. Free energy profiles for the oxidative addition of MeI to complex R in CHCl₃ 64

Figure ‎3.20. Free energy profiles for the oxidative addition of MeI to [PtMe (ppz-H)(PPh₃)], R, in two different solvents (CHCl₃ and acetone) 65

Figure ‎3.21. Proposed initiation of the S_N2 oxidative addition (left) and HOMO of transition state TS in the reaction of [PtMe(ppz-H)(PPh₃)], R, with MeI in CHCl₃ 67

Figure ‎3.22. Selected frontier orbitals, HOMO and LUMO of complex R.. 68

Figure ‎3.23. Selected frontier orbitals, HOMO and LUMO of TS. 68

Figure ‎3.24. Selected frontier orbitals, HOMO and LUMO of complex Pʹ 69

List of Schemes

Scheme Page

Scheme 1.1. Cyclometalation reactions. 13

Scheme 1.2. Cyclometalation reaction with heat 14

Scheme 1.3. Oxidative addition of the substrate X-Y to a metal center (M) 17

Scheme 3.1. The synthetic pathway of cis/trans-[PtCl₂(SMe₂)₂] 36

Scheme 3.2. The synthetic pathway of [Me₂Pt(m-SMe₂)₂PtMe₂] 38

Scheme 3.3. The synthetic pathway of [PtMe₂(DMSO)₂] 40

Scheme 3.4. The synthetic pathway of [PtMe(ppz-H)(DMSO)] 42

Scheme 3.5. The synthetic pathway of [PtMe(ppz-H)(PPh₃)] 46

Scheme 3.6. The synthetic pathway of [PtMe₂I(ppz-H)(PPh₃)] 50

Scheme 3.7. Suggested mechanism for reaction of MeI with [PtMe(ppz-H)

(PPh₃)] 59

Scheme 3.8. Oxidative addition reaction of the platinum(II) complex with MeI. 61

امتیاز 0 از 5 از 0 دیدگاه

قیمت اصلی 35,000 تومان بود.قیمت فعلی 21,000 تومان است.

تاریخ ایجاد دی 7, 1399
تاریخ بروزرسانی اسفند 13, 1401
فروش 0
دیدگاه 0

شرایط استفاده از محصول

تمام محصولات به ازای پرداخت پروژه تنها قابل استفاده می باشند. این بدین معنی است که برای استفاده از یک یا چند محصول ، لازم به خرید آن محصول است.

مزایای خرید این محصول:

دسترسی به فایل به صورت همیشگی
پشتیبانی رایگان
پشتیبانی 24 ساعته محصول
بازگشت وجه در صورت عدم رضایت مشتری

مشاهده قوانین سایت