DOCSLIB.ORG

Ligand Substitution Reactions: Overview

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Ligand Substitution Reactions: Overview Organometallic Reactions I: Reactions That Occur at the Metal Ligand Substitution Oxidative Addition Reductive Elimination Actors and spectators Actor ligands are those that dissociate or undergo a chemical transformation (where the chemistry takes place!) Spectator ligands remain unchanged during chemical transformations They provide solubility, stability, electronic and steric influence (where ligand design is !) Ligand Substitution Ligand substitution reactions: overview Studied systematically for the reactions of phosphines with metal carbonyls (Basolo) Classification D Dissociative (comparable to the SN1 limiting case) A Associative (comparable to the SN2 limiting case) I Interchange / Intermediate • Ia (comparable to typical SN2 reactions) • Id (comparable to typical SN1 reactions) Notes: "Labile" and "Inert" are kinetic terms "Stable" and "Unstable" are thermodynamic terms Ligand Substitution Reactions Substitution reactions can be: Associative (SN2) Dissociative (SN1) They can involve - 2e ligands: CO, PR3 C2H4, … one electron ligands. Ligand Substitution Reactions The following trends have been observed 1. M-L bonds from two-electron donors such as CO are at most half as strong as the familiar C-H and C-C bonds in organic chemistry, thus dissociative mechanisms are possible. 2. Polyhapto ligands such as η6- cyclopentadienyl and η6-arene have much stronger M-L bonds than CO and will not undergo dissociative substitution Ligand Substitution Reactions 3. M-L bond strengths in general increases down a triad as third row> second row > first row. Note that there are many exceptions. 4. The general order of bond strengths has been established: Cp > MexC6H6-x > C6H6 > CO ~ PMe3 ~ Olefin > PPh3 >Py > CH3CN >THF , acetone, ethanol Dissociative Mechanism Only bond breaking is involved in the formation of an intermediate of decreased coordination number. Typical of 18e- complexes Dissociative displacements Observed for 18e carbonyls 8 10 6 Rates: d > Td d > Oh d Y-intermediate is favored by L being a good π-donor; T- intermediate is favored by a high trans-effect L. Rates for TM: 3rd row < 2nd row > 1st row Dissociation is accelerated for bulky ligands. Weakly bound solvent molecules are often useful ligands synthetically. Associative substitutions Often adopted by 16e complexes: Found for 18e complexes that have a ligand which can rearrange (slip): Associative Mechanism Bond making is involved in the formation of an intermediate or transition state of increased coordination number. Associative Mechanism Bond making is involved in the formation of an intermediate or transition state of increased coordination number. Fast Associative mechanisms are typical of 16e- complexes. Associative Mechanism Associative substitution reactions involving coordinatively unsaturated 16- electron systems are relatively fast (rates ~ 104 sec). Rearrangements of coordinatively unsaturated species When a ligand dissociates, one of the remaining ligands rearranges to fill the vacant site created: the reverse of the slippage process. Analogous to neighboring group participation in organic chemistry Synthesis: nucleophilic attack on the metal Very useful and rather general method Common reagents are RLi, RMgX (or R2Mg), ZnR2, AlR3, BR3, and PbR . 4 15 Ligand Substitution Reactivity of Coordinated Ligands Why care about substitution ? Basic premise about metal-catalyzed reactions: Reactions happen in the coordination sphere of the metal Reactants (substrates) come in, react, and leave again Binding or dissociation of a ligand is often the slow, rate- determining step This premise is not always correct, but it applies in the vast majority of cases. Notable exceptions: Electron-transfer reactions Activation of a single substrate for external attack peroxy-acids for olefin epoxidation CO and olefins for nucleophilic attack Dissociative ligand substitution Example: Factors influencing ease of dissociation: 1st row < 2nd row > 3rd row 8 10 6 d -ML5 > d -ML4 > d -ML6 stable ligands (CO, olefins, Cl-) dissociate easily (as opposed to e.g. CH3, Cp). Dissociative substitution in ML6 16-e ML5 complexes are usually fluxional; the reaction proceeds with partial inversion, partial retention of stereochemistry. The 5-coordinate intermediates are normally too reactive to be observed unless one uses matrix isolation techniques. Associative ligand substitution Example: Sometimes the solvent is involved. Reactivity of cis-platin: Ligand Rearrangement Several ligands can switch between n-e and (n-2)-e situations, thus enabling associative reactions of an apparently saturated complex: Redox-induced ligand substitution Unlike 18-e complexes, 17-e and 19-e complexes are labile. Oxidation and reduction can induce rapid ligand substitution. Reduction promotes dissociative substitution. Oxidation promotes associative substitution. In favourable cases, the product oxidizes/reduces the starting material ⇒ redox catalysis. Redox-induced ligand substitution Initiation by added reductant. Sometimes, radical abstraction produces a 17-e species Photochemical ligand substitution Visible light can excite an electron from an M-L bonding orbital to an M-L antibonding orbital (Ligand Field transition, LF). This often results in fast ligand dissociation. Requirement: the complex must absorb, so it must have a color! or use UV if the complex absorbs there Photochemical ligand substitution Some ligands have a low-lying π* orbital and undergo Metal-to- Ligand Charge Transfer (MLCT) excitation. This leads to easy associative substitution. The excited state is formally (n-1)-e ! Similar to oxidation-induced substitution HOMO LUMO M-M bonds dissociate easily (homolysis) on irradiation ⇒ (n-1)-e associative substitution Electrophilic and nucleophilic attack on activated ligands Electron-rich metal fragment: ligands activated for electrophilic attack. H2O is acidic enough to protonate this coordinated ethene. Without the metal, protonating ethene requires H2SO4 or similar. Electrophilic and nucleophilic attack on activated ligands Electron-poor metal fragment: ligands activated for nucleophilic attack. BuLi does not add to free benzene, it would at best metallate it (and even that is hard to do). Electrophilic attack on ligand Hapticity may increase or decrease. Formal oxidation state of metal may increase. Electrophilic Addition Is formally oxidation of Fe(0) to FeII (the ligand becomes anionic). Ligand hapticity increases to compensate for loss of electron. Electrophilic abstraction Electrophilic abstraction + + also by Ph3C , H Alkyl exchange also starts with electrophilic attack: Electrophilic attack at the metal If the metal has lone pairs, it may compete with the ligand for electrophilic attack Transfer of the electrophile to the ligand may then still occur in a separate subsequent step Electrophilic attack at the metal Can be the start of oxidative addition (although this could also happen via concerted addition) Key reaction in the Monsanto acetic acid process: One reaction, multiple mechanisms Concerted addition, mostly with non-polar X-Y bonds H2, silanes, alkanes, O2, ... Arene C-H bonds more reactive than alkane C-H bonds (!) Intermediate A is a σ-complex. Reaction may stop here if metal-centered lone pairs are not readily available. Final product expected to have cis X,Y groups. One reaction, many applications Oxidative addition is a key step in many transition-metal catalyzed reactions Main exception: olefin polymerization The easy of addition (or elimination) can be tuned by the electronic and steric properties of the ancillary ligands The most common applications involve: a) Late transition metals (platinum metals) b) C-X, H-H or Si-H bonds Many are not too sensitive to O2 and H2O and are now routinely used in organic synthesis. Oxdative addition, reductive elimination The Heck reaction Pd often added in the form of Pd2(dba)3. dba, not quite an innocent ligand Usually with phosphine ligands. Typical catalyst loading: 1-5%. But there are examples with turnovers of 106 or more Heterogenous Pd precursors can also be used, but the reaction itself happens in solution The Heck reaction For most systems, we don't know the coordination environment of Pd during catalysis. At best, we can detect one or more resting states. The dramatic effects of ligand variation show that at least one ligand is bound to Pd for at least part of the cycle. The Heck reaction Works well with aryl iodides, bromides Slow with chlorides Hardly any activity with acetates etc. Challenges for "green chemistry" Pt is ineffective Probably gets "stuck" somewhere in the cycle Suzuki and Stille coupling Glorified Wurtz coupling Many variations, mainly in the choice of electrophile Instead of B(OH)2 or SnMe3, also MgCl, ZnBr, etc The Suzuki and Stille variations use convenient, air-stable starting materials Suzuki and Stille coupling The oxidative addition and reductive elimination steps have been studied extensively. Much less is known about the mechanism of the substitution step. The literature mentions "open" (3-center) and "closed" (4-center) mechanisms This may well be different for different electrophiles. Association-Dissociation of Lewis acids Lewis acids are electron acceptors, e.g. BF3, AlX3, ZnX2 H H W: + BF3 W BF3 H H This shows that a metal complex may act as a Lewis base The resulting bonds are weak and these complexes are called adducts Association-Dissociation of Lewis bases A Lewis base is a neutral, 2e ligand “L” (CO, PR3, H2O, NH3,
Load more

Recommended publications
  • The Photochemical Properties of Arene Metal Carbonyl Complexes of Group 6 and 7 Elements
    THE PHOTOCHEMICAL PROPERTIES OF ARENE METAL CARBONYL COMPLEXES OF GROUP 6 AND 7 ELEMENTS DCU THIS THESIS IS PRESENTED FOR THE DEGREE OF DOCTOR OF PHILOSOPHY AT DUBLIN CITY UNIVERSITY BY Peter Brennan B.Sc. UNDER THE SUPERVISION OF DR. MARY PRYCE AND PROF. CONOR LONG SCHOOL OF CHEMICAL SCIENCES FEBRUARY-2003 DECLARATION I hereby certify that this thesis, which I now submit for assessment on the programme of study leading to the award of Doctor of Philosophy is entirely my own work and has not been taken from the work of others save and to the extent that such work has been cited and acknowledged within the text of my work Signed :________________________ Date :_________________________ Peter Brennan Student ID No. 97970646 Table of contents Page Title i Declaration ii Table of contents iii Acknowledgements ix Abstract x Chapter 1 Literature survey 1.1 Introduction to the chemistry of organometallic complexes 2 1.2 UV/vis monitored flash photolysis 8 1.3 Time Resolved InfraRed (TRIR) Spectroscopy 10 1.3.1 Step scan TRIR spectroscopy 10 1.3.2 Point by point TRIR 12 1.4 Matrix isolation 14 1.5 Bonding in M-CO complexes 19 1.6 Metal - Arene bonding 24 1.7 The electronic absorption spectra of (fi6-arene)Cr(CO)3 complexes 26 1.8 Photochemistry of (ri6-arene)M(CO)3 complexes 27 1.9 Photochemistry of (r|S-CsHs)Mn(CO)3 complexes 32 1.10 Arene exchange reactions 35 1.11 Ring slippage reactions 41 1.12 The Indenyl ligand effect 43 1.13 References 46 Chapter 2 The photochemistry of substituted arene metal carbonyls 2.1 Introduction to the photochemistry
    [Show full text]
  • Dissociative Ligand Substitution
    Dissociative Ligand Substitution Associative substitution is unlikely for saturated, 18-electron complexes—coordination of another ligand would produce a 20-electron intermediate. For 18-electron complexes, dissociative substitution mechanisms involving 16- electron intermediates are more likely. In a slow step with positive entropy of activation, the departing ligand leaves, generating a coordinatively unsaturated intermediate. The incoming ligand then enters the coordination sphere of the metal to generate the product. For the remainder of this post, we’ll focus on the kinetics of the reaction and the nature of the unsaturated intermediate (which influences the stereochemistry of the reaction). The reverse of the first step, re-coordination of the departing ligand (rate constant k–1), is often competitive with dissociation. A general scheme for dissociative ligand substitution. There’s more to the intermediate than meets the eye! Reaction Kinetics Let’s begin with the general situation in which k1 and k–1 are similar in magnitude. Since k1 is rate limiting, k2 is assumed to be much larger than k1 and k–1. Most importantly, we need to assume that variation in the concentration of the unsaturated intermediate is essentially zero. This is called the steady state approximation, and it allows us to set up an equation that relates reaction rate to observable concentrations Hold onto that for a second; first, we can use step 2 to establish a preliminary rate expression. (1) rate = k2[LnM–◊][Li] Of course, the unsaturated complex is present in very small concentration and is unmeasurable, so this equation doesn’t help us much. We need to remove the concentration of the unmeasurable intermediate from (1), and the steady state approximation helps us do this.
    [Show full text]
  • Toward the Upgrading of Hydrocarbons: Synthesis, Characterization, and Reactivity of Platinum and Palladium Complexes
    Toward the Upgrading of Hydrocarbons: Synthesis, Characterization, and Reactivity of Platinum and Palladium Complexes Thesis by Paul Frederick Oblad In Partial Fulfillment of the Requirements for the degree of Doctor of Philosophy CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2012 (Defended August 26, 2011) 2012 Paul Frederick Oblad All Rights Reserved ii Acknowledgements I have so many people to thank for their role in my education. First and foremost, I have all of my advisors to mention. John Bercaw and Harry Gray have been very generous in letting me join their groups as a refugee from Jonas Peters’ group. John has been a great advisor, as he provided both direction and supervision when I needed it and freedom to pursue my interests when I was so inclined. Harry has been an eternal optimist and always providing me much needed direction and support. He taught me to laugh at my mistakes and, more importantly, how to correct them. I feel that I would not have been able to learn as much as I have from John and Harry if I had worked for any other advisor. I am also tremendously grateful to Jay Labinger. Though he was not officially responsible for me, he gave his time like he was. Jay was always available when I had questions and was able to answer those questions in a way that even I could understand. Jay Winkler was also an unofficial advisor that generously gave his time. His door was always open to me and he would patiently answer all of my questions. Also, even though he was only my advisor for a short time, I am very grateful to Jonas Peters for his role in my education.
    [Show full text]
  • Organometallic Chemistry
    Chem 4571 Organometallic Chemistry Lecture Notes Prof. George G. Stanley Department of Chemistry Louisiana State University 614 Choppin Hall 578-3471 E-Mail: [email protected] Spring, 2006 (updated 1/15/2006) Class A, B, & C oxidative addition substrate labels dropped. Some new, clearer mechanisms in hydrogenation and hydroformylation chapters. New material added to polymerization chapter (metathesis polymerization, late TM polymerization). New chapter on Pd-catalyzed coupling rxns (by Prof. Lionel Delaude, University of Liege in Belgium). Intro 2 Chemistry 4571 - Organometallic Chemistry (Sp 2006) Prof. George G. Stanley (office: Choppin 614, phone: 578-3471) E-Mail: [email protected] Tuesday - Thursday Lecture 9:10 AM - 10:30 AM Williams 103 This is an advanced undergraduate, introductory graduate level course that covers the organometallic chemistry of the transition metals with emphasis on basic reaction types and the natural extensions to the very relevant area of homogeneous (and heterogeneous) catalysis. An outline of the course contents is shown below: A. Ligand Systems and Electron Counting 1. Oxidation States, d electron configurations, 18-electron "rule" 2. Carbonyls, Phosphines & Hydrides 3. σ bound carbon ligands: alkyls, aryls 4. σ/π-bonded carbon ligands: carbenes, carbynes 5. π-bonded carbon ligands: allyl, cyclobutadiene, cyclopentadienyl, arenes. B. Fundamental Reactions 1. Ligand substitutions 2. Oxidative addition/Reductive elimination 3. Intramolecular insertions/eliminations [4. Nucleophillic/Electrophillic attacks on coordinated ligands (brief coverage, if any)] C. Catalytic Processes 1. Hydrogenation: symmetric and asymmetric 2. Carbonylations: hydroformylation and the Monsanto Acetic Acid Process 3. Polymerization/oligomerization/cyclizations Web Site: chemistry.lsu.edu/stanley/teaching-stanley.htm. Class materials will be posted on the web.
    [Show full text]
  • Organometallic Reactions R
    2/9/2021 Organometallic reactions R. H. Crabtree: The organometallic chemistry of the transition metals Pages 207 - 234 1 Organometallic reaction steps • Ligand dissociation / coordination Me3Al + NMe3 Me3Al-NMe3 6e 8e note: free Me3Al dimerizes to Me6Al2 Mo(CO)6 Mo(CO)5 + CO 18e 16e 2 1 2/9/2021 Organometallic reaction steps • Insertion and b-elimination (details in the 5th lecture) MeMgBr + MeC N Me2C=NMgBr Also possible: (opposite reaction is not common) 3 Organometallic reaction steps • Oxidative addition / Reductive elimination (details in the 6th lecture) 4 2 2/9/2021 Organometallic reaction steps • s-bond metathesis Often: early TM with d0 configuration • Redox reactions - e- Fe Fe • Homolysis Et Hg Et Et Hg + Et 5 Reactivity of coordinated ligands • Basic premise about metal-catalyzed reactions: • Reactions happen in the coordination sphere of the metal • Reactants (substrates) come in, react, and leave again • Binding or dissociation of a ligand is often the slow, rate-determining step • This premise is not always correct, but it applies in the vast majority of cases. Notable exceptions: • Electron-transfer reactions • Activation of a single substrate for external attack • peroxy-acids for olefin epoxidation • CO and olefins for nucleophilic attack 6 3 2/9/2021 Dissociative ligand substitution Factors influencing ease of dissociation: • For 18e complexes • 1st row < 2nd row > 3rd row ’ if [CO] or k-1 are very small 8 10 6 strong trans-effect • d -ML5 > d -ML4 > d -ML6 ‘ • stable ligands (CO, olefins, Cl-) dissociate easily (as opposed to e.g. CH3, Cp) • Weakly bound molecules (solvent) useful synthetically -donor Easily replaced by a reactant • Dissociation accelerated for large ligands PPh3 • Chemical promotion of dissociation: M-Cl by Ag+; RH by H+; 7 Associative ligand substitution L' - L Example: LnM LnM L' Ln-1M L' 16 e 18 e 16 e Sometimes the solvent is involved.
    [Show full text]
  • Activation Strain Analyses of Reactivity Trends Received: 29 June 2018 Pascal Vermeeren 1, Xiaobo Sun 1 & F
    www.nature.com/scientificreports OPEN Arylic C–X Bond Activation by Palladium Catalysts: Activation Strain Analyses of Reactivity Trends Received: 29 June 2018 Pascal Vermeeren 1, Xiaobo Sun 1 & F. Matthias Bickelhaupt 1,2 Accepted: 3 July 2018 We have quantum chemically explored arylic carbon–substituent bond activation via oxidative Published: xx xx xxxx insertion of a palladium catalyst in C6H5X + PdLn model systems (X = H, Cl, CH3; Ln = no ligand, PH3, (PH3)2, PH2C2H4PH2) using relativistic density functional theory at ZORA-BLYP/TZ2P. Besides exploring reactivity trends and comparing them to aliphatic C–X activation, we aim at uncovering the physical factors behind the activity and selectivity. Our results show that barriers for arylic C–X activation are lower than those for the corresponding aliphatic C–X bonds. However, trends along bonds or upon variation of ligands are similar. Thus, bond activation barriers increase along C–Cl < C–H < C–C and along Pd < Pd(PH3) or Pd(PH2C2H4PH2) < Pd(PH3)2. Activation strain analyses in conjunction with quantitative molecular orbital theory trace these trends to the rigidity and bonding capability of the various C–X bonds, model catalysts, and ligands. Catalysis plays a key role in many industrial processes, as well as in the synthesis of various biologically active com- pounds1–3. An important class of catalytic processes is constituted by transition-metal-catalyzed cross-coupling reactions which furnish new carbon–carbon bonds (Fig. 1)4,5. Te frst and commonly the rate-determining step in the catalytic cycle of a typical cross-coupling reaction is the activation of a carbon–substituent bond (R–X) by oxidative addition to a transition metal complex.
    [Show full text]
  • Ligand Substitution
    Mashhad of University FerdowasiInorganic Synthesis 1 Synthesis of Organometallic Compounds Mashhad • Organometallic compounds refer to thoseof containing at least one metal-carbon bond. • They are in an interdisciplinary area between inorganic and organic chemistry. University • Organometallic compounds have played a critical role in catalysis and organic synthesis, often leading to a more efficient use of reagents, higher yields of products, and less use of energy. 2 Ferdowasi Synthesis of Organometallic Compounds Mashhad • Organometallic compounds have also beenof used as precursors in the preparation of nanomaterials and microelectronic materials such as thin films in integrated circuits University • Species containing M-C bonds have been found in biology as well. The vitamin B12 coenzyme: Co-C bond 3 Ferdowasi Mashhad • synthetic methods: of • (1) reactions between metal species and preformed ligands or ligand precursors Grignard reagents, organolithiumUniversityreagents, M(CH2But)4, and MeCo(CO)4 4 Ferdowasi Mashhad • synthetic methods: of • (2) reactions of ligands in organometallic compounds yielding new ligand • the synthesis of Fischer carbeneUniversityand carbyne complexes containing M=C and M-C bonds ands. 5 Ferdowasi SYNTHETIC REACTIONS TO PREPARE ORGANOMETALLIC COMPLEXES Mashhad • ligand substitution of • oxidative addition and reductive elimination • insertion and elimination of ligands • nucleophilic and electrophilicUniversity attack on coordinated ligands 6 Ferdowasi SYNTHETIC REACTIONS Mashhad • LIGAND SUBSTITUTION of Associative Substitution Dissociative Substitution University Interchange Type 7 Ferdowasi SYNTHETIC REACTIONS • LIGAND SUBSTITUTION Mashhad of • Ligand substitutions are often the first and last steps in a catalytic cycle which makes them a common reaction type in organometallic chemistry. • This type of reactions usuallyUniversity occurs at the metal with no overall change in oxidation state or coordination number.
    [Show full text]
  • Reaction Kinetics and Mechanisms in Coordination Compounds
    Reaction kinetics and mechanisms in coordination compounds The kinetics of inorganic reaction mechanism The mechanism of a chemical reaction is understood from transition state theory. The course of a chemical reaction involves collision of reactants sufficiently energetic to form the activated complex or transition state. Along the path from reactants to products kinetic energy is converted into potential energy by bond stretching, partial bond formation, angular distortions etc. The transition state is the species of maximum potential energy resulting from these motions. All energetically unfavourable processes have occurred by the time a transition state is reached. Activation energy: The energy required for the reactant to reach the transition state from ground state is called the activation energy. After the transition state, the collection of atoms rearranges toward more stable species: old bonds are fully broken, new bonds are fully made, and geometric rearrangement toward a more stable configuration (Relaxation) occurs. In multistep reactions a new transition state is reached for each distinguishable step. Plots can be made of the energy of a reacting system as a function of relative atomic positions. Consider the reaction, H2 + F → HF + H When all reactants are confined to a straight line, the distances between atoms are rH-H and rH-F describes relative atomic positions. The path which involves changes in both rH-H and rH-F is called reaction coordinate. A plot of energy verses two variable is three dimensional. Principle of microscopic reversibility Whether any reaction proceeds forward or backward, it follows the reaction coordinate. Atomic positions simply reverse themselves as the reaction is reversed, like a film shown backwards.
    [Show full text]
  • This Is the Peer Reviewed Version of the Following Article: Mrózek, O., Vinklárek, J., Růžičková, Z
    This is the peer reviewed version of the following article: Mrózek, O., Vinklárek, J., Růžičková, Z. and Honzíček, J. (2016), Indenyl Compounds with Constrained Hapticity: The Effect of Strong Intramolecular Coordination. Eur. J. Inorg. Chem., 2016: 5250–5264. doi:10.1002/ejic.201601029 This article may be used for non-commercial purposes in accordance With Wiley-VCH Terms and Conditions for self-archiving". This postprint version is available from http://hdl.handle.net/10195/67606 FULL PAPER Indenyl compounds with constrained hapticity: effect of strong intramolecular coordination. Ondřej Mrózek,[a] Jaromír Vinklárek,[a] Zdeňka Růžičková,[a] and Jan Honzíček*[b] Abstract: A series of cyclopentadienyl and indenyl called “indenyl effect” has been initially attributed to enhanced molybdenum(II) compounds with intramolecularly coordinated stability of η3-intermediates in the association reaction pathway pyridine arm, including scorpionate-like species bearing two as a consequence of the aromatic gain of the adjacent six- irreversibly coordinated arms on indenyl core, was synthesized membered ring.[5] Although this approach is sometimes still and characterized. All presented structural types were confirmed accepted, it neglects different thermodynamic stability of η5-Cp by X-ray diffraction analysis. Due to π-basicity of pyridine, the and η5-Ind species that may play a crucial role in rearrangement intramolecular interaction is considerably stronger than in case as revealed by Veiros et al.[6] They have demonstrated that the of analogous species bearing tertiary amines in the side chain. acceleration of associative substitution reactions is a direct Although the starting compounds for syntheses are isostructural, consequence of the different bonding of the ligands to the metal the reaction outcomes differ considerably.
    [Show full text]
  • Nxumalo Mthobisi Ian 2018.Pdf (4.274Mb)
    A Kinetic and Mechanistic Study of Cyclic Amine Functionalized Platinum(II) Complexes with Bio-Relevant Nitrogen Nucleophiles By Mthobisi Ian Nxumalo BSc. (Hons.) (University of KwaZulu-Natal) School of Chemistry and Physics University of KwaZulu-Natal Pietermaritzburg 3209 i A Kinetic and Mechanistic Study of Cyclic Amine Functionalized Platinum(II) Complexes with Bio-Relevant Nitrogen Nucleophiles By Mthobisi Ian Nxumalo A thesis submitted in fulfilment of the requirements for the degree of Master of Science School of Chemistry and Physics University of KwaZulu-Natal Pietermaritzburg 3209 Table of Contents Declaration.......................................................................................................................................................... i Abstract ............................................................................................................................................................. iii Acknowledgements .......................................................................................................................................... v Abbreviations .................................................................................................................................................. vi Ligands .......................................................................................................................................................... vi Other Abbreviations ................................................................................................................................
    [Show full text]
  • Kinetic Study and Linear Free Energy Relationship Analysis of Some Metal Carbonyl Complexes
    KINETIC STUDY AND LINEAR FREE ENERGY RELATIONSHIP ANALYSIS OF SOME METAL CARBONYL COMPLEXES Jianbin Hao A thesis submitted in conformity with the requirements for the degree of Doctor of Philosophy Graduate Department of Chemistry University of Toronto @ Copyright by Jianbin Hao 1997 National Library Bibliothèqus nationale du Canada Acquisitions and Acquisitions et Bibliographie Services services bibliographiques 395 Wellington Street 395. nie Wellington OttawaON KtAON4 Ottawa ON K1A ON4 Canada Canada The author has granted a non- L'auteur a accordé une licence non exclusive licence allowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or sell reproduire, prêter, distribuer ou copies of this thesis in microfom, vendre des copies de cette thèse sous paper or electronic formats. la fome de microficiche/film, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fkom it Ni la thèse ni des extraits substantiels may be printed or othemise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. KINETIC STUDY AND LINEAR FREE ENERGY RELATIONSEIIP ANALYSIS OF SOME METAL CARBOlYYL COMPLEXES Jianbin Bao, Doctor of Philosophy thesis 1997 Depmmtent of Chemistry, University of Toronto The kinetics of CO-substitution reactions with various P- and As-donor nucleophiles of RU~(CO)~~L(L = P(OPh)3, P(O-i-Pr)3, PCy3, P(II-BU)~and PPhEt2) and Ru~C(CO)~~L(L = P(OPh), and PCy3) have been studied.
    [Show full text]
  • The Organometallic Chemistry of the Transition Metals
    THE ORGANOMETALLIC CHEMISTRY OF THE TRANSITION METALS THE ORGANOMETALLIC CHEMISTRY OF THE TRANSITION METALS Sixth Edition ROBERT H. CRABTREE Yale University, New Haven, Connecticut Copyright © 2014 by John Wiley & Sons, Inc. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at http://www.wiley.com/go/permissions. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate.
    [Show full text]