Investigation of Uranium Tris(imido) Complexes: Synthesis, Characterization, and Reduction Chemistry of [U(NDIPP)₃(thf)₃]

Abstract

Addition of KC8 to trivalent [UI3(thf)4] in the presence of three equivalents of 2,6-diisopropylphenylazide (N3DIPP) results in the formation of the hexavalent uranium tris(imido) complex [U(NDIPP)3(thf)3] (1) through a facile, single-step synthesis. The X-ray crystal structure shows an octahedral complex that adopts a facial orientation of the imido substituents. This structural trend is maintained during the single-electron reduction of 1 to form dimeric [U(NDIPP)3{K(Et2O)}]2 (2). Variable-temperature/field magnetization studies of 2 show two independent U(V) 5f (1) centers, with no antiferromagnetic coupling present. Characterization of these complexes was accomplished using single-crystal X-ray diffraction, variable-temperature (1)H NMR spectroscopy, as well as IR and UV/Vis absorption spectroscopic studies.

Synthesis and Reduction of Uranium(V) Imido Complexes with Redox‐Active Substituents

“…[67] Uranium(V) complexes with arylimido ligandsa lso exhibited similarU= N-C bond angles;aseries of uranium(V) imido complexes reported by Kiplinger,G raves, and co-workers,( C 5 Me 5 ) 2 U V [=NDipp)]X (X = Cl, Br,I ,OTf, SPh, NPh 2 ), had U = N-C bond angles ranging from 169.6(4)8 when X = Cl to 174.0(3) when X = NPh 2 . [44] Compound 4 had arelatively short U=Nb ond lengtho f1 .9503 (14) compared with this series, whichr anged from 1.9575(5) when X = OTf to 1.984(4) when X = NPh 2 .…”

“…In these compounds, the steric properties of the amide and imido ligands determinedt he overall geometry of the compounds. In compounds 2 and 3,t he imido ligand was the mosts terically demanding, which causedt he N = U-N amide bond angle to be largea tt he expense of decreasing the (5), U(1)ÀN(4) 1.960 (5), N(4)ÀC(19) 1.486 (7),C (19)-N(4)-U(1) 179.3 (4), N(4)-U(1)-N(1) 113.13 (19), N(1)-U(1)-N(2) 105.33(17);3-U(1)ÀN(1) 2.269(6), U(1)ÀN(2) 1.956 (9), N(2)ÀC(7) 1.502 (14), C(7)-N(2)-U(1) 180.000 (2), N(2)-U(1)-N(1) 115.23 (15), N(1)-U(1)-N(1) 103.15(18);4-U(1)ÀN(1) 1.9503 (14), U(1)ÀN(2) 2.2313 (14), U(1)ÀN(3) 2.2529 (14), U(1)ÀN(4) 2.2469 (14), N(1)ÀC(1) 1.387(2), C(1)-N(1)-U(1)172.32 (13), N(1)-U(1)-N(2) 99.51, N(2)-U(1)-N(3) 115.42 (5). N amide -U-N amide bond angles and lengthening the UÀN amide bonds.…”

“…[4][5][6][7][8] The studyo fU À Nm ultiple bondingi sm ore limited, although it has recently achieved milestone discoveries in the isolation of the first exampleso ft erminal molecular uranium nitride, [9][10][11] terminal parenti mido, [12] and uranium tris(imido) moieties. [13,14] Presently,t here are an umber of high-valent uraniumb is(imido) complexes reported in the literature, [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] as well as uranium mono(imido)c omplexes in the uranium + 4, [24][25][26][27][28][29][30][31][32][33][34][35] + 5, [36][37][38][42][43][44][45][46] and + 6 [36,37,…”

Elucidating bonding preferences in tetrakis(imido)uranate(VI) dianions

“…18). For 2-Li to 2-Cs, the energy of these vibrations trends with the hardness of the cation present.…”

Steric control of redox events in organo-uranium chemistry: synthesis and characterisation of U(v) oxo and nitrido complexes

“…U( ii ) 3 ) and also the study of higher oxidation state complexes featuring U···E (E = main group element) multiple bonds. 4 Historically, complexes featuring U···O terminal bonds have been dominated by the ubiquitous uranyl moiety, 5 partly due to its apparent chemical inertness (although recently disproved 6 ) and its technological relevance to the nuclear cycle. 7 In contrast, terminal mono-oxo complexes are much less common partly due to the increased nucleophilicity of the oxo ligand, 4u , 8 which leads to the formation of dimeric species, 8a , 9 and stabilisation of monomeric U O complexes requires the use of bulky supporting ligands.…”