Chemistry ETDs

Author

Agnes Mrutu

Publication Date

2-9-2011

Abstract

Selective oxidation chemistry is a topic of intense interest worldwide, in particular when using molecular oxygen (O2) directly as the oxidizing species. The primary reason for using O2 rather than other oxidants is to take advantage of the inexpensive nature of oxygen; however, the radical ground state of O2 leads to non-selective reactions with organic substrates. As such, basic knowledge and understanding involving the fundamental reactions of O2 with organometallic species will be required in order to overcome this lack of selectivity. The work presented in this dissertation has two main research goals to help address this issue. First, we have synthesized and characterized a number of various pincer-carbene containing Ni and Pd hydrides. We have postulated that these species might function as homogeneous catalysts to deliver O atoms to various organic or inorganic substrates. Second, we are interested in demonstrating the reactions of these carbene complexes with O2. As both the precursors and O2 reaction products of carbene-pincer complexes have been studied only briefly previously, we anticipated that our studies would add to the fundamental understanding of these complexes. Specifically, syntheses and characterization of novel pincer carbene Pd-H complexes was achieved. The pincer carbene Pd-H complex proved reactive with O2; however, the isolation of a discrete Pd-OOH species was unsuccessful. Investigation of the oxygen transfer ability of these complexes was done through in situ reaction of Pd-H species, O2 and organic substrates. However, there was no evidence indicating oxygen transfer to the organic substrates. New pincer carbene Pd and Ni complexes were prepared and characterized through alternative routes to M-H or M-OOH. Although none of these routes led to isolation of M-OOH species, MeCCC-Pd-OTf reacted with H2O2/H2O to form MeCCC-Pd-OH. Further investigation on this reaction suggested that the desired Pd-OOH species may initially be formed which slowly decomposed to the Pd-OH species. Attempts to prepare carbene pincer Ni-H complexes and their precursors via a variety of routes resulted in several novel reaction products. We have prepared and structurally-characterized the first example of a unique dinuclear Ni compound containing MeCNC ligands in both bridging and chelating modes. As well, we have obtained a new 3-dimensional Ag-carbene coordination polymer obtained through a novel reverse transmetallation. This result is only the second case in which carbene transfer from Ni2+ to Ag+ is observed.

Project Sponsors

Department of Energy through a grant to Professors R. A. Kemp and K. I. Goldberg (Grant # DE-FG02-06ER15765).

Language

English

Keywords

Pincer carbene ligands, Pd complexes, Dinuclear Ni complexes, Ag clusters

Document Type

Dissertation

Degree Name

Chemistry

Level of Degree

Doctoral

Department Name

Department of Chemistry and Chemical Biology

First Advisor

Kemp, Richard

First Committee Member (Chair)

Lattman, Michael

Second Committee Member

van Swol, Frank

Third Committee Member

Deck, Lorraine

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