Trivalent metallocene chemistry of some uranium, titanium, and zirconium complexes

Thesis/Dissertation · Mon May 01 00:00:00 EDT 1995

DOI:https://doi.org/10.2172/111895· OSTI ID:111895

Lukens, Jr., Wayne Wendell ^[1]

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1. Univ. of California, Berkeley, CA (United States)

Dicyclopentadienyluranium halide dimers have been prepared and their solution behavior examined. These molecules exist as dimers in solution, and the halide ligands undergo rapid site exchange on the NMR timescale above 50 C. Analogous dicyclopentadienyluranium hydroxide dimers have also been prepared; they oxidatively eliminate hydrogen to give the corresponding oxide dimers. Mechanism of this reaction is consistent with αmigration of one of the hydroxide hydrogen atoms to a uranium center followed by elimination of hydrogen. Ground state of [(Me₃Si)₂C₅H₃]₃M M = Nd, U and their base adducts has been examined by variable temperature magnetic susceptibility and EPR spectroscopy. The ground state is found to be ⁴I_9/2 with a crystal field state consisting largely of J_z = 1/2 lowest, in agreement with previous studies on tris-cyclopentadienylneodymium complexes. The zirconium metallocene Cp₃Zr has been prepared, characterized crystallographically, and its reactivity studied. Its chemical behavior is controlled by presence of an electron in the non-bonding, d_z2 orbital which prevents formation of base adducts Of Cp₃Zr, but allows Cp₃Zr to abstract atoms from other molecules. Electonic and EPR spectra of Cp*₂TiX complexes, where Cp* is Me₅C₅ and X is a monodentate, anionic ligand such as halide, have been studied. A π-bonding spectrochemical series is developed, and trends in π-bonding ability are found similar to those in other inorganic complexes. The β-agostic interactions in Cp*₂TiN(Me)Ph have been examined using variable temperature EPR spectroscopy, and the enthalpy/entropy of the interaction determined. In Cp*₂TiEt, enthalpy of the β-agostic interaction is -1.9 kcal/mol. The titanocene anion, Cp*₂TiLi(TMEDA) (TMEDA is N,N,N`,N`-tetramethylethylenediamine), has been prepared and its structure determined.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE; National Science Foundation (NSF)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 111895
• Report Number(s): LBL-37646; ON: DE96001061; TRN: 95:023245
• Resource Relation: Other Information: TH: Thesis (Ph.D.); PBD: May 1995
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
URANIUM COMPLEXES
CHEMISTRY
ZIRCONIUM COMPLEXES
TITANIUM COMPLEXES
CYCLOALKENES
NMR SPECTRA