Chemistry Commons^™

Selective Oxygen Atom Insertion Into An Aryl-Palladium Bond, Ava Behnia, Paul D. Boyle, Johanna M. Blacquiere, Richard J. Puddephatt

Chemistry Publications

The chemistry of a palladium(II) complex containing both an alkyl- and an aryl-palladium bond is reported. The reaction of [Pd(CH2CMe2C6H4)(MesN=CHCH=NMes)] with bromine or iodine leads to reductive elimination of 1,1-dimethylcyclobutabenzene with formation of [PdX2(MesN=CHCH=NMes)] (X = Br, I). However, the reaction with hydrogen peroxide gives [Pd(CH2CMe2C6H4O)(MesN=CHCH=NMes)] by overall oxygen atom insertion into the aryl-palladium rather than the alkyl-palladium bond. This complex [Pd(CH2CMe2C6H4O)(MesN=CHCH=NMes)] reacts with bromine, iodine, or hydrogen peroxide to give 3,3-dimethyl-2,3-dihydrobenzofuran and the corresponding complex [PdX2(MesN=CHCH=NMes)]. The mechanisms of reaction and basis for selectivity are discussed. The results support the view that oxygen atom insertion is a mechanistically viable …

Reactions Of Platinum Complexes With Dimethylamine-Borane, Shawn M. Robinson

Electronic Thesis and Dissertation Repository

This thesis describes a study of the reactions of platinum complexes with dimethylamine-borane (DMAB) as models for alkane activation. It is concluded that sigma-borane complexes of platinum(II) or platinum(IV) will be difficult to synthesize or even to detect as intermediates in hydride transfer from boranes to platinum.

The complex [PtMe(O₂CCF₃)(bpy)] reacts with DMAB to form an intermediate [PtMeH(bpy)] complex, which undergoes reductive elimination of methane with further degradation to give platinum(0) and free 2,2’-bipyridine. The addition of methyl acrylate to the reaction allowed the trapping of the platinum-hydride, producing [PtCl(CHMeCO₂Me)(bpy)] and [Pt(CHMeCO₂Me) …

Reactivity Of Dimethylplatinum (Ii) Complexes, Muhieddine A. Safa

Electronic Thesis and Dissertation Repository

This thesis describes a study of dimethylplatinum(II) and dimethylplatinum(IV) complexes containing bidentate nitrogen donor ligands. This work deals with oxidative addition, and reductive elimination chemistry, and it focuses on synthesis, characterization, and reaction mechanisms in studies of these complexes.

The compound [PtMe₂(bpe)], bpe = 1,2-bis(2-pyridyl)ethane, is easily oxidized to give octahedral organoplatinum(IV) complexes and the subsequent chemistry is profoundly influenced by the accompanying strain induced in the 7-membered Pt(bpe) chelate ring. On reaction of [PtMe₂(bpe)] with HCl, the initial product [PtHClMe₂(bpe)] undergoes reductive elimination of methane to form [PtClMe(bpe)]. In contrast, methyl …

Fluoride-Promoted Ligand Exchange In Diaryliodonium Salts, Bijia Wang, Ronald Cerny, Shriharsha Uppaluri, Jayson J. Kempinger, Stephen G. Dimagno

Stephen DiMagno Papers

Diaryliodonium salts are shown to undergo rapid, fluoride-promoted aryl exchange reactions at room temperature in acetonitrile. Aryl exchange is shown to be exquisitely sensitive to the concentration of fluoride ion in solution; fast exchange is observed as the fluoride concentration approaches a stoichiometric amount at 50 mM substrate concentration. The reaction is slowed, but not halted if benzene is the solvent, indicating that free fluoride ion or a four-coordinate anionic I(III) species may be responsible for the exchange. The fluoride-promoted aryl exchange reaction is general and allows direct measurement of the relative stabilities of diaryliodonium salts featuring different aryl substituents. …

Controlling Reductive Elimination From Novel I(Iii) Salts Using A Secure Method, Joseph W. Graskemper

Department of Chemistry: Dissertations, Theses, and Student Research

Positron Emission Tomography (PET) is a valuable clinical, research, and diagnostic technique for human and animal organ imaging. The current market for PET in the United States is $500 million per year and is projected to be $5.4 billion per year globally by 2015. To synthesize labeled radiotracers, we are most interested in using ¹⁸F as the isotope of choice because it is a nearly ideal positron emitting radionuclide.

Electron-rich aromatic substrates can be particularly difficult to fluorinate. We show that reductive elimination of I(III) diaryliodonium salts provide increased fluorination of electron-rich aromatic substrates. Modest yields of fluorinated product …

Functionalization Of Aromatic Organic Molecules By Anhydrous Flourides And By Reductive Elimination Of Iodine(Iii), Bijia Wang

Department of Chemistry: Dissertations, Theses, and Student Research

Solution phase reactivity of nucleophilic fluoride reagents is attenuated by ion-pairing interactions. ¹H-¹⁹F HOESY competition experiments permit generation of a fluoride ion affinity scale in the weak-binding regime. Direct DFT calculations of ion pair interaction energies as well as calculated cation electrostatic potential maps can be used to predict solution phase ion pairing tendencies for closely related ammonium cations. It was found by studying the decomposition of tetra-substituted ammonium cations by fluoride that: 1) rates of E2 decomposition is faster than the S_N2 pathway; 2) aryl substituents destabilize the cations; 3) steric strain tends to …

Regiospecific Reductive Elimination From Diaryliodonium Salts, Bijia Wang, Joseph W. Graskemper, Linlin Qin, Stephen G. Dimagno

Stephen DiMagno Papers

StereoElectronic Control of Unidirectional Reductive Elimination (SECURE) is provided by the cyclophane substituent on iodine(III). Computational and experimental studies demonstrate that out of plane steric bulk strongly destabilizes the reductive elimination transition state, and leads to regiochemical control. This approach should be general for high valent main group and transition metal ions.