Nitrogen based monodentate and bidentate chelating ligands have captured a significant interest due to their ability to coordinate to a wide variety of elements. The â-diketimine, â-ketoiminato, formamidine, pyridineselenolate, and pyrazinecarboxamide ligands have all been employed in this study to further investigate the coordination preferences among main group and transition metals. Steric and electronic properties of these ligands can easily be altered by manipulating the substituents attached, thus leading to predictable structures with potential for many useful and significant applications. Investigations have shown that temperature, solvent, and metal halide employed are all key factors in the reaction outcomes. All of the complexes obtained throughout these studies have been characterized by X-ray crystallography along with other spectroscopic techniques, including NMR, IR, UV/Vis, and M/S.
â-diketiminato ligands, [{N(R)C(Me)}2C(H)] where R = Dipp, Mes, commonly referred to as nacnac, have played an important role in the synthesis of novel pnictogenium complexes. Results show that through manipulation of the halide precursor, reaction stoichiometry, and the R substituent on the nacnac both N,N'- and N,C'-metal chelated complexes can be achieved.
Additionally, â-ketiminato ligands, [RN(H)(C(Me))2C(Me)=O] where R = Dipp, and [RN(H)C(Me)CHC(Me)=O] where R = C2H4NEt2, have been studied. Both ligands were investigated with a range of d and p block metal halides and alkyls in order to compare and contrast the bulky, flexible, and even multi-dentate nature of each ligand. The preferred metal geometry remains constant for products with either ligand, but the steric protection offered by the individual ligands governs the nuclearity of the products, ranging from tetrameric cages to simple adducts.
The formamidinate ligand, [RN(H)C(H)NR] where R = Dipp, was employed in synthesizing several aluminum and zinc complexes. In addition to their numerous applications as catalysts, the smaller ligand backbone is capable of N,N'-chelation analogously to the â-diketiminates and â-ketiminato ligands, as well as a variety of other coordination modes. The stoichiometric ratio of ligand to the metal alkyl was emphasized for these reactions affording aluminum and zinc formamidinate complexes exhibiting monodentate, bidentate, and bridging coordination modes.
Lastly, the coordination of group 13 metal halides was investigated employing the pyridineselenolate, [HSe-2-NC5H4], and pyrazinecarboxamide, [(C4H3N2)CONH2], ligands. The research focused on the individual synthetic methods in the preparation of group 13 complexes.
| Identifer | oai:union.ndltd.org:TCU/oai:etd.tcu.edu:etd-01162009-164206 |
| Date | 16 January 2009 |
| Creators | Lesikar, Leslie |
| Contributors | Anne F Richards |
| 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-01162009-164206/ |
| 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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