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42768-GB3
Determination of the Catalytic Activity of a Rhenium Bisdithiolene Complex as a Homogeneous and Heterogeneous Catalyst for Oxygen Atom Transfer Reactions
Since Sept 1, 2006 there have been minimal results achieved on the project. Instead there have been presentations of the previous findings at two national conferences. Dr. Zauche presented a poster at the Feb 2007 Gordon Conference, Inorganic Reaction Mechanisms. Rebecca Johnson, a student who worked over the summer of 2005 on the project, presented her findings at the ACS National Meeting held in Chicago in 2007. Miss Johnson is now attending graduate school at UW-Madison after a summer internship with Archer Daniels Midland.
To assist in the synthesis and purification of the Rhenium catalyst, a Biotage flash chromatography system was purchased this year. The students as well as Dr. Zauche were trained in its use. It turned out however, that the rhenium complex did not behave on the system as on TLC, i.e. it did not separate using the flash system. The company specialists even carried out the chromatography and did not achieve separation of products.
To better understand the formation of the rhenium complex, the rate of coordination of rhenium with the alkyne ligand was studied via UV-Vis detection. This study provided us with knowledge that will lead to higher yields for the attachment of rhenium to a solid support.
The addition of the rhenium-alkyne species also led to a dual time curve when hydrogen peroxide was added. That is, there was a fast step and a much slower step. The second slower step may be due to a decomposition pathway that we hope to eliminate by coordination to the resin support. However, at this time we have not completed our studies of structural determination and reactivity of the rhenium complex bound to a resin support. There is another student working on the project this year for a senior thesis. We anticipate synthesis of the attached rhenium to the solid support and carrying out some studies using an NMR with a rhenium probe at Madison's campus thanks for Clark Landis.
