INOR 354 |
| The homolysis of the Ti-O bond of Cp2TiCl(TEMPO) (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) is facile at 60°C to generate the transient Cp2Ti(III)Cl and the stable nitroxyl radical, TEMPO. Experimental and theoretical studies reveal the strength of the Ti-O bonds for biscyclopentadienyl Ti-TEMPO complexes to be on the order of 25 kcal/mol, whereas those for monocyclopentadienyl Ti-TEMPO complexes, such as CpTiCl(TEMPO), are on the order of 40 kcal/mol. Theoretical calculations reveal that the magnitude of these Ti-O bond strengths depends sensitively on the ancillary ligation at titanium and predict that monocyclopentadienyl Ti-TEMPO complexes containing pendant donor ligands would exhibit lower bond energies than CpTiCl(TEMPO). To confirm these predictions, we have prepared a series of monocyclopentadienyl Ti complexes containing pendant donors and nitroxyl ligands to evaluate the influence of both pendant donors and nitroxyl ligands on the structure and stability of the Ti-TEMPO complexes. These Ti-TEMPO complexes have also been evaluated for the copolymerization of ethylene and styrene. |
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Radical Metal Complex Chemistry
7:00 PM-10:00 PM, Sunday, 10 September 2006 Moscone Center -- Hall D, Poster
Division of Inorganic Chemistry |