Studies of electron-withdrawing phosphorus ligands for hydroformylation, and of an iron-chromium methoxycarbyne complex.
Item
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Title
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Studies of electron-withdrawing phosphorus ligands for hydroformylation, and of an iron-chromium methoxycarbyne complex.
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Identifier
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AAI9959204
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identifier
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9959204
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Creator
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Luo, Wei.
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Contributor
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Adviser: William H. Hersh
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Date
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2000
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Language
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English
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Publisher
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City University of New York.
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Subject
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Chemistry, Organic | Chemistry, Inorganic
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Abstract
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Part 1. Three new iron-chromium heterodinuclear compounds, [Cp(CO)Fe(mu-CO)2Cr(CO)(eta6-C6H 6)]-Na+ (6-Na+), [Cp(CO)Fe(mu-CO) 2Cr(CO)(eta6-C6H6)] -[PPN+] (6-PPN+) [PPN+ = bis(triphenylphosphine)nitrogen(+1)] and Cp(CO)Fe(mu-COCH 3)(mu-CO)Cr(CO)(eta6-C6H6) (7) were prepared. Cis/trans isomerization of 6-Na + was observed by 1H and 13C NMR to occur remarkably rapidly in CD3CN. Isomerization of methoxycarbyne 7 is slower but still rapid by comparison to related compounds. Thermal decomposition of 7 at 50°C in C6D6 with and without PPh3 provides just the fourth example of oxygen to metal methyl migration in a methoxycarbyne complex. However, it is the first example in which a methoxycarbyne follows kinetics in which the values of the rate constants are independent of phosphine concentration. This decomposition results in the cleavage of the iron-chromium bond. The use of these compounds in non-linear optical applications is considered, but the metal-metal cleavage may limit their utility in the preparation of novel mixed metal materials.;Part 2. Hydroformylation of 1-hexene and 1-octene was carried out in THF using Rh(acac)(CO)2 as a catalyst precursor in the presence of a variety of aminophosphine additives. The electron-withdrawing chelating ligand N,N'-bis(diphenylphosphino)- N, N'-di-p-toluenesulfonyl-1,2-edmediamine (diTosL) gives the highest yields (>80%) and regioselectivity, favoring the formation of the linear aldehyde over the branched aldehyde by a ∼10: 1 ratio. A monodentate analog of diTosL and an N-methyl electron-donating analog each give rise to lower yields and much lower regioselectivity. Attempts to prepare modified diTosL analogs with more rigid backbone linkages failed due to the high degree of steric hindrance around both nitrogen atoms. Two new chelating analogs of 2-phenyl-1,3-di-ptoluenesulfonyl-1,3,2-diazaphospholidine (TosL) were also prepared, but they are insoluble in common hydroformylation solvents. In the solvent in which they are soluble, DMF, no hydroformylation is observed to occur. We propose that DMF is more strongly coordinating than these weakly coordinating ligands towards rhodium, resulting in the loss of catalytic ability of the ligands.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
