Nitride, imide, and azide chemistry of anilide-supported tungsten and uranium complexes by Alexander Ray Fox.

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.