|Document Type:||Master's Thesis|
|Title:||Synthetic Routes to 3-Fold Symmetric Tridentate Oxygen Donor Ligands|
|Degree:||Master of Science|
|Committee Chair:||Dr. Brian E. Hanson|
|Keywords:||tridentate ligands, Oxygen donor ligands, phosphite synthesis, organometallics, anionic liigands|
|Date of defense:||August 1, 1997|
|Availability:||Release the entire work for Virginia Tech access only.
After one year release worldwide only with written permission of the student and the advisory committee chair.
The class of ligands represented by [CpCo(P(O)(OR)2)3]-, L- , were first synthesized by W. Kläui in 1977. These ligands have been found to coordinate to a variety of low and high oxidation state metals through the use of its three P=O oxygen atoms as donors. The ligands act as mono-anionic six electron donors which make them similar to the more widely known cyclopentadienyl ligands, (C5H5-xRx)-, but have electronic properties like those of fluoride or oxide. Also, it has been found that the coordination chemistry of L- resembles the unsubstituted tris(pryrazolyl)hydroborato six electron ligand, (RB(pz)3)-. All three of these ligands can be modified by changing the substituent R. The Kläui ligand offers a good opportunity to synthesize a chiral derivative. In the process to obtain the chiral version, (cyclopentadienyl)tris(biphenyl-phosphito-P)cobaltate(1-), 18, was synthesized from 2,2’-biphenol. This was characterized through NMR, mass spectroscopy, and XPS. Next, a racemic version, (cyclopentadienyl)tris(biphenylphosphito-P)cobaltate(1-), 17, was synthesized from (±)1,1’-bi-2-naphthol. A one-pot synthesis for the rac-binaphthyl phosphite derivative was developed with an increased yield from the previously published synthesis. The racemic version of the ligand was characterized by NMR and mass spectroscopy. The chiral version has not yet been synthesized, however, by following the developed procedure for the non-chiral version, the ligand could be synthesized from optically active 1,1’-bi-2-naphthol.
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