Synthesis, Characterization and Reactivity of Imido Chromium(VI) Complexes

Synthesis, Characterization and Reactivity of Imido Chromium(VI) Complexes
Author: Pengcheng Wu
Publisher:
Total Pages: 288
Release: 2019
Genre:
ISBN: 9780438931831

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This dissertation describes research on imido chromium(VI) complexes. The relative instability of the highest oxidation state and the weaker metal-bonds of the first-row metal generally make for sparse organometallic chemistry of hexavalent chromium. The motivation of my research is to make high valent chromium complexes supported by imido ligands and explore their reactivity in C-H activation, olefin metathesis and the activation of other small molecules (e.g. PhNCO, CO2).

Synthesis, Characterization and Catalytic Activity of Chromium Complexes

Synthesis, Characterization and Catalytic Activity of Chromium Complexes
Author: Joanna Gurnham
Publisher:
Total Pages: 0
Release: 2014
Genre: University of Ottawa theses
ISBN:

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There has been a growing demand for specific linear alpha olefins in the polyethylene industry in order to control polymer rheology. This growing demand thereby increases the need for highly active and selective ethylene oligomerization catalysts. Chromium-based catalysts continue to be of high interest for this application due to this metal's versatility in both selective and non selective ethylene oligomerization. Ligand design is an important consideration in oligomerization chemistry: the ability of the ligand to stabilize low valent chromium and to support a two-electron redox process will allow the catalytic systems to follow the selective ring expansion mechanism for oligomerization. Chelating aminophosphane based ligands, previously studied by our group, have been shown to support both tri- and tetramerization of ethylene. We have explored modifications of one of the NP arms by replacing with a different coordinating group in an attempt to further stabilize the monovalent state of chromium and increase selectivity. Other ligands explored in this work are pyrrole based ligands, which have shown high activity and selectivity towards ethylene oligomerization. One example of this is the commercial Chevron-Phillips system. Recently, the co-polymerization of CO2 with epoxides has been studied as an environmentally friendly route to convert CO2 into biodegradable polymers. The first successful catalytic system to achieve these results consisted of a diethyl-zinc complex. More recently, aluminum, chromium, cadmium and cobalt have been studied as polycarbonate catalysts. To date, the only reported chromium catalysts for CO2-epoxide copolymerization are Cr-salen and Cr-porphyrin complexes, studied by Darrensbourg and Holmes, respectively. We were particularly interested in finding new chromium-based complexes able to catalyze epoxide/CO2 copolymerization by using molecules with the nitrogen donor motif embedded in different functions such as neutral pyridines with anionic pendants, pyrroles with either imine or amine pendants, or a combination of these.

Vanadium and Chromium Complexes Supported by Sterically Demanding Ligands

Vanadium and Chromium Complexes Supported by Sterically Demanding Ligands
Author: Nathan Christopher Smythe
Publisher:
Total Pages: 414
Release: 2006
Genre:
ISBN:

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(Cont.) Chapter 4. TRAP (P(CH2CH2NH2)3), a phosphine containing analogue to TREN (N(CH2CH2NH2)3) was synthesized from PH3, but suitable conditions for arylation of the amine arms could not be found. Using the "pre-arylated" arm BrCH2CH2N(BOC)HIPT (BOC = tert-butoxycarbonyl; HIPT = 3,5-(2,4,6-i-Pr3C6H2)2C6H3) in the reaction with PH3 resulted in the isolation of H2PCH2CH2N(BOC)HIPT, but further substitution was unsuccessful. HIPTBr could be converted to HIPTNH2 using benzophenone imine and a rac-BINAP (2,2'-bis(diphenylphosphino)-1,1'-binaphthyl) supported Pd catalyst in preparation for DCC (dicyclohexylcarbodiimide) mediated coupling to tris-(3-propylcarboxylicacid)phosphine.

Activation of Small Molecules

Activation of Small Molecules
Author: William B. Tolman
Publisher: John Wiley & Sons
Total Pages: 382
Release: 2006-12-13
Genre: Science
ISBN: 3527609377

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The first to combine both the bioinorganic and the organometallic view, this handbook provides all the necessary knowledge in one convenient volume. Alongside a look at CO2 and N2 reduction, the authors discuss O2, NO and N2O binding and reduction, activation of H2 and the oxidation catalysis of O2. Edited by the highly renowned William Tolman, who has won several awards for his research in the field.