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Document Type

Dissertation - University Access Only

Award Date

1992

Degree Name

Doctor of Philosophy (PhD)

Department / School

Chemistry

First Advisor

Henry Gehrke, Jr.

Abstract

The main purpose of the study was to investigate the effects that solvent purity, dioxygen, time, and added triphenylphosphine have on the mode of the reaction of ReOCl3 (PPh3)2 in chloroform. The goal was achieved by using sealed tube reactions with an air or argon atmosphere at increased temperature. As a result of this work, it was found that the source of the excess oxygen, for the formation of oxygen containing compounds in the sealed tube reaction of ReOCl3 (PPh3)2 with reagent grade chloroform, was dioxygen rather than water or the ethanol present in the chloroform. The principle products isolated in this reaction are ReCl4 (PPh3)2, cis and trans- ReCl4 (OPPh3)2, and ReCl4 (PPh3) (OPPh3). The percent of ReCl4 (OPPh3)2 isolated increases and the percent of ReCl4 (PPh3)2 decreases as the reaction time is increased. The percent of cis- ReCl4 (OPPh3)2 isolated reaches a maximum with a 6 hour reaction time. Conversion to the trans configuration does not occur at reflux temperature. However, the conversion is quantitative in a sealed tube after 12 hours. The crystal structure of cis- ReCl4 (OPPh3)2 was also determined. When triphenylphosphine is added to the sealed tube containing ReOCl3 (OPPh3)2 with reagent grade chloroform, the major product is [MePPh3]2ReCl6. The yield of [MePPh3]2ReCl6 is decreased when sealed under air. The source of the methyl group is the reaction of triphenylphosphine with chloroform, followed by the subsequent reaction of PPh3CHCl with alcohol. This reaction appears to be catalyzed by a rhenium moiety. If triphenylphosphine is added to the sealed tube containing ReOCl3 (PPh3)2 and ethanol free chloroform, [MePPh3]2ReCl6 is not isolated. The products are (CH2PPPh3)2ReCl6, a purple compound, and [PPh3CH2PPh3]Cl2·nH20. The crystal structure of (CH2PPPh3)2ReCl6 was determined. Isolation of this unique compound indicates that some of the triphenylphosphine must undergo complete loss of the phenyl groups. The purple compound has been determined to be a mixture of trans- ReCl4 (OPPh3)2 and an unidentified compound. The formation of [PPh3CH2PPh3]Cl2·nH20 is independent of the formation of (CH2PPPh3)2ReCl6. The formation of [PPh3CH2PPh3]Cl2·nH20 is the result of triphenylphosphine reacting with the ethanol free chloroform. Identification of (PPh3CH2PPh3]Cl2·nH20 was confirmed by the crystal structure of [PPh3CH2PPh3][FeCl4]2 ·2H20.

Library of Congress Subject Headings

Chloroform
Rhenium compounds
Chemical reactions

Format

application/pdf

Publisher

South Dakota State University

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