[PDF] Synthesis Characterization And Redox Studies Of Platinum And Palladium Complexes With Mer Coordinating Ligands eBook
Synthesis Characterization And Redox Studies Of Platinum And Palladium Complexes With Mer Coordinating Ligands Book in PDF, ePub and Kindle version is available to download in english. Read online anytime anywhere directly from your device. Click on the download button below to get a free pdf file of Synthesis Characterization And Redox Studies Of Platinum And Palladium Complexes With Mer Coordinating Ligands book. This book definitely worth reading, it is an incredibly well-written.
Synthetic, structural, spectroscopic, and redox studies of platinum(II) and palladium(II) compounds with mer-coordinating ligands have been undertaken in an effort to better understand the role of the metal and the ligands in controlling d^6/d^8 electron-transfer reactions. A series of Pd(pip2NCN)X (pip2NCNH=1,3-bis(piperdylmethyl)benzene) and [Pd(pip2NNN)X]X (X=Cl, Br, I) (pip2NNN=2,6- bis(piperdyl-methyl)pyridine) complexes are reported. Electronic spectra are consistent with stabilization of ligand-to-metal-charge-transfer states as the ancillary ligand is varied along the ClBr
Kyle A. Grice, Margaret L. Scheuermann and Karen I. Goldberg: Five-Coordinate Platinum(IV) Complexes.- Jay A. Labinger and John E. Bercaw: The Role of Higher Oxidation State Species in Platinum-Mediated C-H Bond Activation and Functionalization.- Joy M. Racowski and Melanie S. Sanford: Carbon-Heteroatom Bond-Forming Reductive Elimination from Palladium(IV) Complexes.- Helena C. Malinakova: Palladium(IV) Complexes as Intermediates in Catalytic and Stoichiometric Cascade Sequences Providing Complex Carbocycles and Heterocycles.- Allan J. Canty and Manab Sharma: h1-Alkynyl Chemistry for the Higher Oxidation States of Palladium and Platinum.- David C. Powers and Tobias Ritter: Palladium(III) in Synthesis and Catalysis.- Marc-Etienne Moret: Organometallic Platinum(II) and Palladium(II) Complexes as Donor Ligands for Lewis-Acidic d10 and s2 Centers.
Author : Nicholas P Farrell Publisher : Royal Society of Chemistry Page : 174 pages File Size : 11,58 MB Release : 2007-10-31 Category : Medical ISBN : 1847552242
Metal-based drugs are a commercially important sector of the pharmaceutical business, yet most bioinorganic textbooks lack the space to cover comprehensively the subject of metals in medicine. Uses of Inorganic Chemistry in Medicine approaches an understanding of the topic in a didactic and systematic manner. The field of inorganic chemistry in medicine may usefully be divided into two main categories - drugs which target metal ions in some form, whether free or protein-bound, and secondly, metal-based drugs where the central metal ion is usually the key feature of the mechanism of action. This latter category can further be subdivided into pharmacodynamic and chemotherapeutic applications, as well as those of imaging. The book summarises the chemical and biological studies on clinically used agents of lithium, gold and platinum, as well as highlighting the research on prospective new drugs, including those based on vanadium and manganese. The coverage allows a clear distinction between pharmacodynamic and therapeutic properties of metal-based drugs and focuses not only on those clinical agents in current use, but also on new drugs and uses. This book serves to fill an important niche, bridging bioinorganic and medicinal chemistry and will undoubtedly be of use to senior undergraduates and postgraduates, as well as being an invaluable asset for teachers and researchers in the discipline.
The importance of Pd-catalyzed C--H functionalization reactions for chemical transformations has been widely studied over the last several decades. Much of the research to date has focused on conventional Pd0/II catalytic cycles. However, more recent studies have shown that many transformations can also follow a PdII/IV catalytic cycle. High-valent PdIII and PdIV species are often proposed to be important intermediates in such transformations. C--H coupling reactions involving high-valent intermediates often involve the oxidation of a PdII species to a PdIII or PdIV complex, which can then undergo subsequent C--heteroatom bond formation. However, the need for harsh oxidants and reaction conditions in many of these reactions hinders their practical applicability. The focus of this work is to study the properties and reactivity of PdII, PdIII, and PdIV complexes through modifications of the supporting macrocyclic ligands. Another goal of this work is to probe the ability of these complexes to facilitate C--H activation and C--heteroatom bond formation reactions using environmentally benign oxidants.Our lab reported the synthesis and characterization of the first organometallic mononuclear PdIII complexes stabilized by the tetradentate ligand N,N'-di-tert-butyl-2,11-diaza[3,3](2,6)pyridinophane (tBuN4). In order to further probe the Pd chemistry with this class of ligands, we prepared ligands with modifications to the steric bulk on the amine groups. In the first study detailed in chapter 2, the synthesis and characterization of PdII and PdIII complexes supported by N,N'-di-neo-pentyl-2,11-diaza[3,3](2,6)-pyridinophane(NpN4) and N,N'-di-benzyl-2,11-diaza[3,3](2,6)-pyridinophane(BzN4) is reported. Interestingly, the spectroscopic and crystallographic property of the newly synthesized complexes falls between the tBuN4 and MeN4 complexes. The C--C and C--heteroatom bond formation reactivity of the NpN4 and BzN4 supported complexes is also similar to our group's previously reported complexes.We also prepared and studied a series of Pd complexes bearing a modified tetradentate pyridinophane ligand, tBuN3CH. Essentially, we have replaced one of the nitrogen donor atoms from the N4 ligand with a carbon atom and have also introduced a new C--H bond. Due to its expected positioning near the metal center, this bond has the potential to undergo intramolecular C--H bond activation. In order to study the reactivity of this ligand, electronic modifications were made by substituting various electron-donating and withdrawing groups in the para position to this new C--H bond. In chapter 3, the synthesis and characterization of a series of PdII, PdIII, and PdIV complexes stabilized by the N3CH ligand is reported. Interestingly, a spectroscopic and crystallographic study of the pRN3CHPdII(OAc)2 complexes reveals that the Cipso--H bond remains unactivated at the PdII stage. However, upon oxidation to PdIII, the Cipso--H bond is activated.Interestingly, we discovered that the aerobic oxidation of the PdII complex [pRN3CHPdII(MeCN)](BF4) leads to the formation of the PdIII complex [pRN3CHPdIII(MeCN)](ClO4)2 at room temperature. Surprisingly, the C--H activation reaction proceeds in the presence of oxygen without the need for external base. Furthermore, the moderate rate of the reaction allowed us to investigate the mechanism of the reaction by utilizing kinetics and UV-Vis spectroscopy. Detailed mechanistic studies revealed that C--H activation of the Cipso--H bond is the rate determining step of the reaction.
Chapter 1 provides an overview of the oxidation of methane by platinum salts known as Shilov chemistry. This includes platinum complexes used for the selective oxidation of methane to methyl bisulfate. Attention is paid to model platinum complexes that have been synthesised to explore the oxidation of methane using dioxygen as the oxidant. Chapter 2 describes two sets of tridentate N donor ligands that have been synthesised. The first set contains 6,6"-disubsthuted-2,2/:6/,2"-terpyridine ligands, of these two new ligands 6,6"-di(methylamino)-2,2/:6/,2"-terpyridine and 6,6"-dimethoxy-2,2/:6/,2"-terpyridine have been synthesised and fully characterised. The second set contains non-terpyridine tridentate ligands. The synthesis and characterisation of novel cationic platinum(II) methyl complexes bearing these ligands is described in Chapter 3. The structures of some of these complexes have been determined by X-ray crystallography. Further, the reactivity of the complexes towards dioxygen is reported and how different reactivity is imparted by the different ligands is discussed. The ability of some of these platinum(II) methyl complexes to insert dioxygen into their M-Me bonds arises from the steric interaction between the Pt-Me ligand and the substituents in the 6- and 6"-positions on the terpyridine ligand. Chapter 4 describes a study into the mechanism of the insertion of dioxygen into a Pt-Me bond. This includes deuterium labelling experiments, which led to the discovery of the exchange of methyl ligands between platinum(II) and palladium(II) centres. A mechanism for this exchange involving the formation of a MII_MII dimer is proposed. In addition, the decomposition of a palladium(II) methylperoxo complex to give an intriguing new metallacyclic hemiacetal alkoxide complex is described. A possible mechanism for the formation of this new palladium(II) complex is discussed. The synthesis and characterisation of the new compounds discussed in Chapters 2-4 are reported in Chapter 5. 4.
ABSTRACT continued: These transfer hydrogenation studies are among the first catalytic studies of silyl-pincer complexes and establish [R-PSiP]M species as viable candidates for catalysis. The synthesis and reactivity of 4- and 5-coordinate RuII complexes featuring the [Cy-PSiP] ligand were explored. Reaction of [Cy-PSiP]H with [(p-cymene)RuCl2]2 in the presence of NEt3 and PCy3 resulted in the formation of ([Cy-PSiP]RuCl)2, which serves as a precursor to a series of unprecedented 4-coordinate, formally 14-electron [Cy-PSiP]RuX (X = NHAr, N(SiMe3)2, OtBu) complexes that feature an unusual trigonal pyramidal geometry at Ru. The reactivity of these novel diamagnetic complexes is described, including the reaction of [Cy-PSiP]RuOtBu with amine-boranes resulting in the formation of rare bis(?-BH) complexes. Computational studies confirmed the key role of the strongly ?-donating silyl group of the Cy-PSiP ligand in facilitating the synthesis of such low-coordinate Ru species and enforcing the unusual trigonal pyramidal geometry. The mechanism of ammonia-borane activation was also examined computationally. Lastly, the synthesis and structural characterization of PdII complexes supported by the pincer-like bis(amino)phosphido ligand [?3-(2-Me2NC6H4)2P]- ([NPN]) is described. Examples of ?1-, ?2-, and ?3-NPN coordination to Pd are described, as is the catalytic activity of ([NPN]PdX)2 (X = Cl, OAc, OTf) complexes in the Heck olefin arylation reaction. In an effort to discourage the formation of phosphido-bridged dinuclear complexes, pre-coordination of the Lewis acid BPh3 to [NPN] was pursued. Upon reaction of [N(P?BPh3)N]K with [PdCl(C3H5)]2, the ?1-allyl complex [?3-N(P?BPh3)N]Pd(?1-C3H5) was isolated, which establishes the coordination of a Lewis acid to the phosphido donor of the [NPN] ligand as a viable strategy for encouraging the formation of mononuclear ?3-NPN complexes.