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Dissertation/Thesis Abstract

Investigation of the 6d and 5f Orbital Contributions in Actinide Complexes Containing Amide, Ketimide, Aryl, and Alkyl Metal-Ligand Bonds
by Seaman, Lani Anne, Ph.D., University of California, Santa Barbara, 2012, 299; 3545129
Abstract (Summary)

Treatment of UCl4 with 6 equiv of LiNHtBu generates the U(IV) amide complex, {[Li(THF)2Cl]2[Li]2[U(NH tBu)6]}n in good yields. Oxidation of {[Li(THF) 2Cl]2[Li]2[U(NHtBu)6]} n with 1 equiv AgOTf results in the formation of the bis(imido) complex [Li(THF)]2[U(NtBu)2(NHtBu) 4]. The reaction of UCl4 with 5 equiv of the secondary amide, LiNC5H10, gives the U(IV) amide complex, [Li(DME)][U(NC 5H10)5]. [Li(DME)][U(NC5H10) 5] is readily amenable to oxidation to generate the U(V) and U(VI) amides, [Li(DME)3][U(NC5H10)6] and U(NC 5H10)6, respectively.

Addition of 5 equiv of LiN=CtBu2 or LiN=C tBuPh to UCl4 results in the formation of either [Li(THF)][U(N=C tBu2)5] or [Li(THF)2][U(N=C tBuPh)5]. Oxidation of [Li(THF)][U(N=CtBu 2)5] with 0.5 equiv I2 generates the U(V) complex, U(N=CtBu2)5. However, oxidation of [Li(THF) 2][U(N=CtBuPh)5] with 0.5 equiv I2 in the presence of 1 equiv of LiN=CtBuPh generates the U(V) complex [Li][U(N=CtBuPh)6]. [Li][U(N=C tBuPh)6] can be oxidized with 0.5 equiv I2 to give the U(VI) complex, U(N=CtBuPh)6. Electronic structure of [Li][U(N=CtBuPh)6] reveals that the strength of the σ- and π-interactions between the ligand 2p and the uranium 5f orbitals is similar to those exhibited by [UX6]. (X = F, Cl, Br).

Reaction of UO2Cl2(THF)3 with 4 equiv of LiNC5H10 results in the formation of the dimeric uranyl complex, [{Li(DME)}2Cl][Li(DME)][UO2(NC 5H10)3]2. [{Li(DME)}2Cl][Li(DME)][UO 2(NC5H10)3]2 exhibits lengthened U=O bond lengths due to the strong σ- and π-donating NC5H 10 ligands. Reaction of UO2Cl2(THF)3 with 4 equiv of Li(NH-2,6-C6H3Me2) generates the monomeric uranyl complex, [Li(THF)(Et2O)]2[UO 2(NH-2,6-Me2C6H3)4], however, U=O activation is not observed. Reaction of UO2Cl2(THF) 3 with 4 equiv of either LiN=CtBu2 or LiN=CtBuPh gives the monomeric uranyl complexes, [Li(THF)(TMEDA)][UO2(N=C tBu2)3] and [Li(THF)(Et2O)] 2[UO2(N=CtBuPh)4], respectively, and U=O bond activation is observed.

Reaction of ThCl4(DME)2 with 5 equiv of either LiCH2 tBu or LiCH2SiMe3 generates the Th(IV) alkyl complexes, [Li(THF)4][Th(CH2 tBu)5] or [Li(DME)2][Th(CH2SiMe 3)5]. Similarly, reaction of ThCl4(DME)2 with 6 equiv KCH2Ph results in the formation of [K(THF)] 2[Th(CH2C6H5)6]2. The stability of these complexes is attributed to saturation of the coordination sphere to form "ate" complexes.

Indexing (document details)
Advisor: Hayton, Trevor
Commitee: Butler, Alison, Seshadri, Ram, Zakarian, Armen
School: University of California, Santa Barbara
Department: Chemistry
School Location: United States -- California
Source: DAI-B 74/04(E), Dissertation Abstracts International
Subjects: Inorganic chemistry
Keywords: Actinides, Alkyl metal-ligand bonds, Amide, Aryl, Ketimide, Orbitals, Thorium, Uranium
Publication Number: 3545129
ISBN: 978-1-267-76828-5
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