â-Diketiminate ligands of the general formula [R<super>3</super>C{C(R<super>2</super>)N(R<super>1</super>)}<sub>2</sub>]<super>-</super> are now among the most ubiquitous chelating systems in all of coordination chemistry. Nacnac (R<super>1</super> = aryl, R<super>2</super> = CH<sub>3</sub>, R<super>3</super> = H) has been used to stabilize of a variety of elements in unusually low oxidation states and in the discovery of a variety of novel bonding modes. We were principally interested in investigating the reactivity of nacnac ligands with selenium and tellurium tetrahalides, due to the absence of group 16 centers in the library of nacnac complexes. To this end we synthesized and characterized the first examples of Se- and Te-nacnac complexes, which avoided the usual N,N'-chelation and instead favored reaction at one of the backbone methyl groups via nucleophilic attack by the carbon-carbon double bond of the enamine form of the ligand.
Additionally, we have utilized two members of the related ketiminate ligand class, of general formula [R<super>1</super>NC(R<super>2</super>)C(R<super>3</super>)C(R<super>2</super>)O]<super>-</super> to synthesize a variety of metal complexes spanning the periodic table. By comparing and contrasting the coordination preferences of a bulkier, bidentate (R<super>1</super> = aryl) ketiminate ligand to that of a more flexible, tridentate (R<super>1</super> = (CH<sub>2</sub>)<sub>2</sub>NEt<sub>2</sub>) ketiminate ligand, we observed a greater ability of the tridentate ligand to stabilize mono-ligated complexes, as opposed to the bis-ketiminato complexes frequently formed using the bidentate ligand. Furthermore, this investigation has led to a wide range of complex types, including monomers, dimers, tetramers, adducts, and hetero-elemental cages.
We have synthesized a series of main group complexes of the commercially available 2,2'-dipyridylamine, an N,N'-chelating ligand not unlike the â-diketiminates. Complexes of this ligand have proven useful in a multitude of applications, in no small part due to the coordinative versatility of this ligand, which can bind in monodentate, bidentate, and tridentate fashions. Finally, we have generated a series of compounds derived from phosphorus ligands based on the bulky trityl (triphenylmethyl = Ph<sub>3</sub>C) group. We have found that the considerable steric bulk of trityl diphenylphosphine inhibits coordination to a variety of metal centers, but novel complexes have been formed by employing the HBF<sub>4</sub> salt of Ph<sub>3</sub>CPPh<sub>2</sub> as the phosphorus-based ligand.
| Identifer | oai:union.ndltd.org:TCU/oai:etd.tcu.edu:etd-10162009-112829 |
| Date | 16 October 2009 |
| Creators | Lugo, Audra Faye |
| Contributors | Anne F. Richards, Do not allow search engine access |
| Publisher | Texas Christian University |
| Source Sets | Texas Christian University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf, application/msword |
| Source | http://etd.tcu.edu/etdfiles/available/etd-10162009-112829/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to TCU or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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