Nitride, imide, and azide chemistry of anilide-supported tungsten and uranium complexes by Alexander Ray Fox.
Name
655318559-MIT.pdf
Description
Full printable version
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40.37 MB
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Checksum (MD5)
a8ce38d94bbda711e2d3702feb212979
Author(s)
Fox, Alexander Ray, 1979-
Advisor(s)
Christopher C. Cummins.
Date Issued
2010
Publisher
Massachusetts Institute of Technology
Abstract
The uranium(III) tris(anilide) complex (THF)U(N[t-Bu]Ar) 3 reacts with MN 3 (M = Na, [N(n-Bu) 4]) to form the bimetallic diuranium(IV/IV) salts M[(p-N)(U(N[t-Bu]Ar) 3)2]. The stability of the U=N=U core across multiple charge states is illustrated by stepwise chemical oxidation of Na[(p- N)(U(N[t-Bu]Ar) 3)2] to the corresponding neutral diuranium(V/IV) and cationic diuranium(V/V) derivatives. Metallonitrene-like reactivity for [(p-N)(U(N[t-Bu]Ar) 3)2][B(ArF) 4] is demonstrated by its reaction with NaCN. The uranium(IV) azide complex (N3)U(N[t-Bu]Ar)3 is prepared by the reaction of the uranium(IV) iodide complex IU(N[t-Bu]Ar)3 with NaN3. Photolysis or reduction of (N3)U(N[t-Bu]Ar) 3 leads to the bimetallic p-nitride system [(-N)(U(N[t-Bu]Ar) 3)2]". The reaction of (THF)U(N[t-Bu]Ar) 3 with the azidoborate salt [N(n-Bu) 4] [(C6F5)3B(N 3)] provides the uranium(V) nitridoborate complex [N(n-Bu) 4] [(C6F5)3BNU(N[t-Bu]Ar) 3], which leads to the neutral uranium(VI) derivative (C6F5)3BNU(N[t-Bu]Ar) 3 by way of le oxidation. A system of uranium complexes featuring bidentate anilide ligands has been developed. The syntheses of the bis(anilide) complexes [(Et20),Li][I2U(N[R]ArMeL)2] and 12U(N[R]ArMeL)2, and the tris(anilide) complexes U(N[R]ArMeL)3 and U(N[Np]ArMeL)3 are described. The N-tert-butylanilide derivative U(N[R]ArMeL)3 fails to react with a host of small molecule substrates but does react with AgOTf to form the separated ion pair [U(N[R]ArMeL)3][OTf], suggesting a high degree of steric encumbrance about the metal center. The N-neopentylanilide derivative U(N[Np]ArMeL)3 reacts with pyridine-N-oxide to form the uranium(V) terminal oxo complex OU(N[Np]ArMeL)3, and with NaN3 to provide the "-ate" complex [Na(THF)6] [(p, T - N3 )(U(N[Np]ArMeL)3)2]- The tungsten(VI) terminal nitride complex NW(N[t-Bu]Ar) 3 is obtained in low but reproducible yield through a route independent of dinitrogen chemistry. The reaction of NW(N[t-Bu]Ar) 3 with electrophiles R-X (R-X = PhC(O)OTf; Mel) provides the four-coordinate imido salts [RNW(N[t-Bu]Ar) 3][X]. The siloxy-substituted ketimide complex Ph(Me 3SiO)CNW(N[t-Bu]Ar) 3 is obtained by reduction and silylation of the benzoylimido salt. In contrast to the chemistry displayed by a related Mo-based system, no reactions that lead to the elimination of PhCN from Ph(Me 3SiO)CNW(N[t-Bu]Ar)3 were uncovered. The parent ketimide complex H2CNW(N[t- Bu]Ar)3 reacts with electrophiles R'-X (R'-X = Me3SiOTf; [Ph 2P][AlC4l4) through the ketimide carbon, providing the substituted methylimido salts [R'CH2NW(N[t-Bu]Ar) 3][X], which in turn provide the substituted ketimide complexes R'(H)CNW(N[t-Bu]Ar) 3 by deprotonation.
Description
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemistry, 2010.
Vita. Page 213 blank. Cataloged from PDF version of thesis.
Includes bibliographical references.
Subjects
Chemistry.
MIT Department
Massachusetts Institute of Technology. Department of Chemistry
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