Author: Alicia L. McDaniel
Publisher:
ISBN:
Category : Chemistry
Languages : en
Pages : 136

Get Book Here

Book Description

Author: Janet Malinda Kessler
Publisher:
ISBN:
Category : Complex compounds
Languages : en
Pages : 488

Get Book Here

Book Description

Author: Evan Freiberg
Publisher:
ISBN:
Category :
Languages : en
Pages : 446

Get Book Here

Book Description
Chapter 1. The chemistry of the metal-metal multiply bonded Tc2(II, II) core has been investigated with bis(diphenylphosphino)methane (dppm). The parent complex, Tc2Cl4(dppm)2, has been prepared from the reaction of Tc2C14(PEt3)4 with dppm. The reactivity of Tc2Cl4(dppm)2 with tert-butyl isocyanide has been studied and a neutral 1:1 adduct, Tc2Cl4(dppm)2CNBut, a cationic 1:2 adduct, [Tc2Cl3(dppm)4(CNBut)2](PF6), and a [mu]-iminyl complex, [Tc2Cl3(dppm)2(CNBut)2CNHBul(PF6), have been prepared. The parent compound and its reaction products have been characterized via a combination of spectroscopic techniques and single crystal X-ray crystallography. The metal-metal bonded ditechnetium bis(dppm) motif is retained in the reaction products. Chapter 2. The reduction of ammonium pertechnetate with bis(diphenylphosphino)methane (dppm), and with diphenyl-2-pyridyl phosphine (Ph2Ppy), has been investigated. The neutral Tc(II) complex, TcCl2(dppm)2, has been isolated from the reaction of (NH4)[TcO4] with excess dppm in refluxing EtOH/HCl. Chemical oxidation with ferricinium hexafluorophosphate results in formation of the cationic Tc(III) analogue, [TcCl2(dppm)2](PF6). The dppm ligands adopt the chelating bonding mode in both complexes, resulting in strained four member metallocycles. With excess PhPpy, the reduction of (NH4)[TcO4] in refluxing EtOH/HCl yields a complex with one chelating Ph2Ppy ligand and one unidentate Ph2Ppy ligand, TcCl3(Ph2Ppy-P, N)(Ph2Ppy-P).

Author: Mary Cecilia Johnson
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

Get Book Here

Book Description
A novel bis-(protic N-heterocyclic carbene, PNHC) phosphine ligand platform is explored to understand its role in CO2 hydrogenation catalysis and as a supporting scaffold for bimetallic complexes. Optimized syntheses for the bis-(PNHC) phosphine ligand and its metalation with a Ru(II) metal center, as well as the synthesis and coordination chemistry of a library of complexes with varying ancillary ligands (2,2’-bipyridine, 4,4’-dibromo-2,2’-bipyridine, 4,4’-dimethoxy-2,2’-bipyridine, and bis-(diphenylphosphino)ethane) are shown. We describe the hydrogenation of CO2 to formate catalyzed by a Ru(II) bis-(protic N-heterocyclic carbene, p-NHC) phosphine complex [Ru(bpy)(MeCN)(PPh(p-NHC)2)](PF6)2 (1). Under catalytic conditions (20 [micromole] catalyst, 20 bar CO2, 60 bar H2, 5 mL THF, 140 °C, 16 hrs) the activity of 1 is limited only by the amount of K3PO4 present in the reaction, yielding a nearly one to one ratio of turn over number (TON) to equivalents of K3PO4 (relative to 1), with the highest TON = 8,040. Additionally, analysis of the reaction solution post-run reveals the catalyst intact with no free ligand observed. Stoichiometric studies, including examination of unique carbamate and hydride complexes as relevant intermediates, were carried out to probe the operative mechanism and understand the importance of metal-ligand cooperativity in this system. We also describe the synthesis and characterization of [Ru(bpy)(solvent)(P(Ph)(NHC)2-K2-N,N'-M(solvent)2)]2+ (M = Co(II), Zn(II)) and subsequent reactivity with hydroxide and formate. Facile inter- and intramolecular cooperation is observed and the structurally responsive NHC-Cobalt-NHC binding pocket is investigated.

Author: Dashawn L. Williams
Publisher:
ISBN:
Category : Complex compounds
Languages : en
Pages : 120

Get Book Here

Book Description

Author: Pantea Menhaji
Publisher:
ISBN:
Category :
Languages : en
Pages : 578

Get Book Here

Book Description

Author: Samantha C. Reynolds
Publisher:
ISBN:
Category :
Languages : en
Pages : 826

Get Book Here

Book Description
Introduction. This chapter provides a brief overview of the thesis. Chapter 1: tert-butyl-diphosphabutarene - Synthesis and reactivity of a novel phosphacycle. Treatment of 1,2-bis(dichlorophosphino)benzene (12) with tert-butylmagesium chloride followed by magnesium powder cleanly forms the air-stable phosphacycle C6H4(P(t-Bu))2 13 as a racemic mixture. Recrystallization of the Pd complex 23, derived from {Pd[(S)-Me2NCH(Me)C10H6]([mu]-Cl)}2, resulted in separtion of diastereomers, which furnished highly enantioenriched 13 on removal of the Pd fragment with dppe (1,2-bis(diphenylphosphino)ethane). Additions across the P-P bond of enriched 13 gave bis(tertiary) phosphines, such as BenzP*. The synthesis, diastereomeric separation via 23, and reactivity of 13 is discussed. Chapter 2: Effect of linker length on the selectivity of pt-catalyzed asymmetric alkylation of Bis(phenylphosphino)alkanes. As part of a broader study of Pt-catalyzed asymmetric alkylation of bis(secondary phosphines), PhHP(CH2)[subscript-n]PHPh (n=2-6), with benzyl bromide, the selectivity of alkylation for substrates with n=2 and n=5 was investigated. For n=3-5, the reaction is catalyst-controlled, whereas the alkylation of PhHP(CH2)2PHPh is substrate controlled. The extent of substrate control in the alkylation of PhHP(CH2)2PHPh is discussed, in addition to the possible structural and mechanistic reasons for this difference in selectivity. Chapter 3: Synthesis and reactivity of bis(secondary phosphines) containing rigid phenylene and quinoxaline backbones. The synthesis and alkylation of several bis(secondary phosphines) containing rigid linkers was attempted. The bis(secondary phosphinobenzenes) 1,2-C6H4(PHR)2 (R=t-Bu (4), Mes (5)) were prepared, but did not undergo selective alkylation with benzyl bromide under a variety of conditions. Quinoxaline-based bis(secondary) phosphines 22a-c were synthesized as part of a mixture, but could not be isolated for further studies. Chapter 4: Synthesis and structure of transition metal-menthyl complexes. A Grignard reagent derived from ( - )-menthyl chloride has been reported to be a 1:1 mixture of menthyl magnesium chloride and neomenthyl magnesium chloride. As part of a broader study, addition of an excess of this Grignard to the metal chloride complexes Au(PPh3)(Cl), Pt(dppe)Cl2 (dppe=Ph2PCH2CH2PPh2), or Pt(dppen)Cl2 (dppen=cis-Ph2PCHCHPPh2) gave Au(PPh3)(Men) (Men=menthly), Pt(dppe)(Men)(Br), and Pt(dppen)(Men)(Br), respectively. This chapter describes the characterization of Au(PPh3)(Men) by 1D and 2D miltinuclear NMR and details the degradation of the Au and Pt complexes in chloroform. Chapter 5: Trans-selective ring opening of limonene oxide with phosphine nucleophiles. Treatment of a 1:1 mixture of cis-and trans-limonene oxide with half an equivalent of lithium primary phosphido nucleophile results in selective attack at the epoxide of the trans-isomer to afford chiral secondary phosphines. Futher reaction of the secondary phosphines may provide a catalogue of P-stereogenic/C-stereogenic tertiary phosphine ligands. The characterization of these phosphines and highly modular nature of the synthesis will be discussed.

Author: Alan Wray Blakely
Publisher:
ISBN:
Category :
Languages : en
Pages : 190

Get Book Here

Book Description

Author: Frank L. Messana
Publisher:
ISBN:
Category :
Languages : en
Pages : 80

Get Book Here

Book Description

Author: Gerard van Koten
Publisher: Springer
ISBN: 3319229273
Category : Science
Languages : en
Pages : 381

Get Book Here

Book Description
The series Topics in Organometallic Chemistry presents critical overviews of research results in organometallic chemistry. As our understanding of organometallic structure, properties and mechanisms increases, new ways are opened for the design of organometallic compounds and reactions tailored to the needs of such diverse areas as organic synthesis, medical research, biology and materials science. Thus the scope of coverage includes a broad range of topics in pure and applied organometallic chemistry, where new breakthroughs are being achieved that are of significance to a larger scientific audience. The individual volumes of Topics in Organometallic Chemistry are thematic. Review articles are generally invited by the volume editors.