Reaction Of UCl4 Research Articles

Uranium Cyanides from Reactions in Liquid Ammonia Solution

AbstractReactions of uranium tri‐ and tetrahalides, UBr3, UI3, UCl4, and UI4, with different cyanides MCN (M=K, Ag) in liquid anhydrous ammonia led to three novel uranium(IV) cyanide compounds. The reaction of UCl4 in the presence of KCN resulted in the compound [U(CN)(NH3)8]Cl3 ⋅ 3NH3, while UBr3 and UI3 were oxidized in the presence of AgCN to form the compounds (μ‐CN){(H3N)5U(μ‐NH2)3U(NH3)5}]Br4 ⋅ 2NH3, and (μ‐CN){(H3N)5U(μ‐NH2)3U(NH3)5}]I4 ⋅ 2NH3. The reaction of UI4 with KCN in aNH3 also yielded the compound (μ‐CN){(H3N)5U(μ‐NH2)3U(NH3)5}]I4 ⋅ 2NH3. The compounds (μ‐CN){(H3N)5U(μ‐NH2)3U(NH3)5}]X4 ⋅ 2NH3 (X=Br, I) crystallize in different space groups, Pmn21 (no. 31) and Imm2 (no. 44), respectively. In both cases, the (μ‐CN){(H3N)5U(μ‐NH2)3U(NH3)5}]4+ cation forms infinite strands. We conducted quantum‐chemical calculations and Intrinsic Bond Orbital analyses on the observed [U(CN)(NH3)8]3+ cation and the [(μ‐CN)2{(H3N)5U(μ‐NH2)3U(NH3)5}]3+ model cation to gain insight into the bonding situation.

Crystallographic and/or magnetic properties of neutral and cationic uranium(IV) sandwiched phthalocyanine complexes

Neutral and cationic U(IV) sandwiched phthalocyanine (Pc) complexes were prepared. The neutral species, UPc2, was obtained by the reaction of UCl4 and phthalonitrile, and the [UPc2][BF4] crystals were grown by electrolysis. The structures of the complexes were determined crystallographically. A U(IV) ion has two 5f electrons, which carry a magnetic moment localized at the U sites, making the complex magnetically active. The magnetic susceptibility measurement of UPc2 revealed that the system was paramagnetic with local magnetic moments down to 2 K, but these magnetic moments were suppressed, possibly by a ligand field effect. The paramagnetism was also confirmed by the magnetization curve without hysteresis. The cationic complex, [UPc2][BF4] crystalized in a tetragonal structure with the space group P4nc, in which the UPc2 molecules stacked along the tetragonal c-axis. The structure was similar to that of [LnPc2][BF4], but with distinct disorder in the stacking plane. The stabilities of the crystal and molecular structures and the electronic configurations of UPc2 and [UPc2][BF4] were evaluated via the ab initio calculations that included the multiconfigurational nature of the actinide element.

Complex Featuring Two Double Dative Bonds Between Carbon(0) and Uranium

Complex Featuring Two Double Dative Bonds Between Carbon(0) and Uranium

Synthesis and Crystallographic Characterization of the Tetravalent Actinide-DOTA Complexes [AnIV(κ8-DOTA)(DMSO)] (An = Th, U)

The reaction of UCl4 or ThCl4(DME)2 (DME = dimethoxyethane) with 1,4,7,10-tetrazacyclododecane-1,4,7,10-tetraacetic acid (H4DOTA), and 6 equiv of triethylamine, in dimethyl sulfoxide (DMSO) results in the formation of [AnIV(κ8-DOTA)(DMSO)] (1, An = U; 2, An = Th), which can be isolated in moderate yields after workup. Complexes 1 and 2 are the first structurally characterized actinide-DOTA complexes to feature the κ8 binding mode for the DOTA ligand. In addition, we isolated a few crystals of [U(κ4-H2DOTA)(DMSO)4][Cl]2 (3). Crystallographic characterization of this material reveals that the [H2DOTA]2- ligand in 3 is only coordinated to U4+ by its four carboxylate arms, generating an overall κ4 binding mode. Similar complexes have been previously proposed as intermediates along the H4DOTA complexation pathway, but this intermediate had not been structurally characterized until now.

Synthesis and Reactivity of a U(IV) Dibenzyne Complex

Reaction of UCl4 with 6 equiv of 2-Li-C6H4CH2NMe2 affords the U(IV) dibenzyne complex [Li]2[U(2,3-C6H3CH2NMe2)2(2-C6H4CH2NMe2)2] (1), which can be isolated as a dark blue solid in 40% yield. Complex 1 represents a rare example of a structurally characterized dibenzyne complex, and its solid-state metrical parameters suggest that the two benzyne ligands are best described with the dianionic metallacyclopropene resonance form. The reactivity of 1 with a variety of electrophiles and oxidants, including benzophenone, 1-azidoadamantane, and benzonitrile, was also explored. Reaction of 1 with 2 equiv of benzophenone affords the insertion product [Li][U(2-C6H3CH2NMe2-3-COPh2)2(2-C6H4CH2NMe2)] (3) as a red-orange solid in 61% yield, concomitant with formation of 1 equiv of 2-Li-C6H4CH2NMe2. Reaction of 1 with 2 equiv of PhCN also affords an insertion product, [Li][Li(Et2O)][U(2,3-C6H3CH2NMe2)(2-C6H3CH2NMe2-3-C(Ph)═N)(2-C6H4CH2NMe2)2] (4), as a green-brown crystalline solid in 21% yield. In an attempt to oxidize 1...

Dithio- and Diselenophosphinate Thorium(IV) and Uranium(IV) Complexes: Molecular and Electronic Structures, Spectroscopy, and Transmetalation Reactivity.

We report a comparison of the molecular and electronic structures of dithio- and diselenophosphinate, (E2PR2)(1-) (E = S, Se; R = (i)Pr, (t)Bu), with thorium(IV) and uranium(IV) complexes. For the thorium dithiophosphinate complexes, reaction of ThCl4(DME)2 with 4 equiv of KS2PR2 (R = (i)Pr, (t)Bu) produced the homoleptic complexes, Th(S2P(i)Pr2)4 (1S-Th-(i)Pr) and Th(S2P(t)Bu2)4 (2S-Th-(t)Bu). The diselenophosphinate complexes were synthesized in a similar manner using KSe2PR2 to produce Th(Se2P(i)Pr2)4 (1Se-Th-(i)Pr) and Th(Se2P(t)Bu2)4 (2Se-Th-(t)Bu). U(S2P(i)Pr2)4, 1S-U-(i)Pr, could be made directly from UCl4 and 4 equiv of KS2P(i)Pr2. With (Se2P(i)Pr2)(1-), using UCl4 and 3 or 4 equiv of KSe2P(i)Pr2 yielded the monochloride product U(Se2P(i)Pr2)3Cl (3Se-U(iPr)-Cl), but using UI4(1,4-dioxane)2 produced the homoleptic U(Se2P(i)Pr2)4 (1Se-U-(i)Pr). Similarly, the reaction of UCl4 with 4 equiv of KS2P(t)Bu2 yielded U(S2P(t)Bu2)4 (2S-U-(t)Bu), whereas the reaction with KSe2P(t)Bu2 resulted in the formation of U(Se2P(t)Bu2)3Cl (4Se-U(tBu)-Cl). Using UI4(1,4-dioxane)2 and 4 equiv of KSe2P(t)Bu2 with UCl4 in acetonitrile yielded U(Se2P(t)Bu2)4 (2Se-U-(t)Bu). Transmetalation reactions were investigated with complex 2Se-U-(t)Bu and various CuX (X = Br, I) salts to yield U(Se2P(t)Bu2)3X (6Se-U(tBu)-Br and 7Se-U(tBu)-I) and 0.25 equiv of [Cu(Se2P(t)Bu2)]4 (8Se-Cu-(t)Bu). Additionally, 2Se-U-(t)Bu underwent transmetalation reactions with Hg2F2 and ZnCl2 to yield U(Se2P(t)Bu2)3F (6) and U(Se2P(t)Bu2)3Cl (4Se-U(tBu)-Cl), respectively. The molecular structures were analyzed using (1)H, (13)C, (31)P, and (77)Se NMR and IR spectroscopy and structurally characterized using X-ray crystallography. Using the QTAIM approach, the electronic structure of all homoleptic complexes was probed, showing slightly more covalent bonding character in actinide-selenium bonds over actinide-sulfur bonds.

Crystal structure of bis[1-{(3,5-dimethyl-1H-pyrazol-1-yl)methyl}-3,5-dimethyl-1H-pyrazol-2-ium] hexachlorouranate(IV): [H2C(3,5-Me2pz)(3,5-Me2pzH)]2[UCl6

The X-ray diffraction study of a single crystal with the composition [H2C(3,5-Me2pz)(3,5-Me2pzH)]2[UCl6] (1) is performed. This compound is the product of an attempted synthesis of a bis(pyrazolyl)methane complex of uranium(IV) obtained by the reaction of UCl4 with bis(3,5-dimethylpyrazol-1-yl)methane in THF. 1 crystallizes in the space group P-1 of the triclinic system: a = 9.6616(2) A, b = 9.6946(2) A, c = 10.7314(2) A, α = 107.6210(10)°, β = 115.5600(10)°, γ = 99.6710(10)°, V = 810.45(3) A3, Z = 1, d calc = 1.765 g/cm3, μ = 5.528 mm−1, R 1 = 0.0249. The structural unit consists of two separated [H2C(3,5-Me2pz)(3,5-Me2pzH)]+ cations and a UCl 6 2− anion. In the solid state structure of 1 several short intermolecular N-H⋯N and C-H⋯Cl contacts are identified suggesting the presence of hydrogen bonds.

Diamido-Ether Actinide Complexes as Catalysts for the Intramolecular Hydroamination of Aminoalkenes

The synthesis and characterization of a series of new diamido-thorium(IV) and diamido-uranium(IV) halide and alkyl complexes supported by three different diamido-ether ligands are reported. Reaction of ThCl4·2DME with [(RNSiMe2)2O]Li2 ([RNON]Li2) in DME when R = tBu gives [tBuNON]ThCl5Li3·DME (1), when R = iPr2Ph in diethyl ether [iPr2PhNON]ThCl3Li·DME (3) is prepared. Reaction of UCl4 with [iPr2PhNON]Li2 in diethyl ether gives {[iPr2PhNON]UCl2}2 (4). Reaction of ThCl4·2DME with Li2[(iPr2PhNCH2CH2)2O] ([iPr2PhNCOCN]Li2) in DME gives [iPr2PhNCOCN]ThCl2·DME (5). The addition of 2 equiv of LiCH2SiMe3 to 1 and 5 resulted in salt- and base-free [tBuNON]Th(CH2SiMe3)2 (7) and [iPr2PhNCOCN]Th(CH2SiMe3)2 (9), respectively. Complexes 1, 3, 4, 7, and 9, as well as previously reported {[tBuNON]UCl2}2 (2), [tBuNON]U(CH2SiMe3)2 (6), and [iPr2PhNCOCN]U(CH2SiMe3)2 (8) were examined as catalysts for the intramolecular hydroamination of a series of aminoalkenes. Complexes 6–9 were shown to facilitate the formation of 2-methyl-4,4-diphenylpyrrolidine from 2,2-diphenyl-1-amino-4-pentene at room temperature. For 9, this reaction occurs in less than 15 min, while for other dialkyls 6–8, the reaction takes less than 2 h. Dihalides 1 and 2 facilitated the same reaction at 60 °C in 4 h, while 3 and 4 showed no activity under the same conditions. Dialkyl complexes 7–9 were examined for further reactivity with different substrates. The uranium dialkyl 8 was more active than 7 and 9 for the cyclization of 2,2-diphenyl-1-amino-5-hexene and 2,2-diphenyl-1-amino-6-heptene, as well as more active in the cyclization of N-methyl-2,2-diphenyl-1-amino-4-pentene, a secondary amine. All three dialkyls became less active when the steric bulk of the gem-substituents was decreased from diphenyl to cyclopentyl; reactivity further decreased when the steric bulk of the substituents was decreased further to hydrogen.

Comparison of the Redox Chemistry of Primary and Secondary Amides of U(IV): Isolation of a U(VI) Bis(imido) Complex or a Homoleptic U(VI) Amido Complex

Reaction of UCl4 with 6 equiv of LiNH(t)Bu generates the U(IV) homoleptic amide complex [Li(THF)2Cl]2[Li]2[U(NH(t)Bu)6] (1 · THF) in 57% yield. In the solid-state, 1 · THF exists as a one-dimensional coordination polymer consisting of alternating [Li]2[U(NH(t)Bu)6] and [Li(THF)2Cl]2 building blocks. Recrystallization of 1 · THF from DME/hexanes affords the monomeric DME derivative, [Li(DME)2ClLi]2[U(NH(t)Bu)6] (1 · DME), which was also characterized by X-ray crystallography. The oxidation of 1 · THF with 1 equiv of AgOTF generates the U(VI) bis(imido) complex [Li(THF)]2[U(N(t)Bu)2(NH(t)Bu)4] (2) in low yield. In contrast, oxidation of 1 · THF with 1 equiv of I2, in the presence of excess tert-butylamine, cleanly affords the U(VI) bis(imido) U(N(t)Bu)2(NH(t)Bu)2(NH2(t)Bu)2 (3) in 78% yield. We have also explored the reactivity of UCl4 with the lithium salt of a secondary amide. Thus, reaction of 6 equiv of (LiNC5H10) (HNC5H10 = piperidine) with UCl4 in DME produces the U(IV) amide, [Li(DME)][U(NC5H10)5] (4). Oxidation of this material with 0.5 equiv of I2, followed by addition of Li(NC5H10), produces [Li(DME)3][U(NC5H10)6] (5) in moderate yield. Oxidation of 5 with 0.5 equiv of I2 generates U(NC5H10)6 (6) in good yield. The structures of 4-6 were elucidated by X-ray crystallographic analysis, while the magnetic properties of 4 and 5 were investigated by SQUID magnetometry. Additionally, the solution phase redox properties of 5 were examined by cyclic voltammetry.

Uranium–hydrogen interactions: synthesis and crystal structures of tris(N,N-dimethylaminodiboranato)uranium(iii)

The reaction of UCl(4) with Na(H(3)BNMe(2)BH(3)) in diethyl ether affords the uranium(III) product U(H(3)BNMe(2)BH(3))(3), which has been crystallized in two different structural isomers depending on the crystallization solvent. Both forms are polymeric, but the nature of the bridging interaction is different in the two forms.

Polyimido Uranium(IV) Clusters: Imidometalates with an M7(μ3‐N)6(μ2‐N)6 Core Analogous to the Anderson‐Type Polyoxometalate Motif

NU clusters: Novel imido uranium(IV) clusters involving four or seven metal centers have been obtained from the reaction of UCl4 and [{PhNMg(thf)}6] in thf or pyridine (see core structure; U yellow, N purple, Cl green, O red). The aggregation is strongly dependent on the nature of the solvent.

Synthesis and reactions of (η5-C5Me4-2-C5H4N)2UCl2 and its derivatives, including the puzzling formation of the ansa-metallocene C2H4(η5-C5Me3-2-C5H4N)2UCl2

Abstract Reaction of UCl4 with Li(C5Me4-2-C5H4N) (LiCp∗Py) gave (Cp∗Py)2UCl2 (1), which was subsequently transformed into (Cp∗Py)2UX2 [X = Me (2), BH4 (3)]. Treatment of 3 with HNEt3BPh4 afforded the cationic derivative [(Cp∗Py)2U(BH4)][BPh4]. The ansa-metallocene C2H4(η5-C5Me3-2-C5H4N)2UCl2 (5) was unexpectedly obtained in one reaction of 2 and CuCl2. The crystal structures of 1 and 5 have been determined.

Uranium(IV) Complexes of Calix[5]arene

AbstractThe μ‐oxo uranium(V) compound [Hpy]2[{U(calix[5]arene–5H)}2(μ2‐O)]·4py (1·4py) was the sole product isolated from the reaction of UCl4 and calix[5]arene unless the last traces of water were eliminated by thoroughly drying the macrocyclic molecule; under such strictly anhydrous conditions, thebinuclear UIV complex [Hpy]3[U2(calix[5]arene–5H)Cl6]·4py (2·4py) was obtained. Treatment of U(OTf)3 or U(OTf)4 (OTf = OSO2CF3) with calix[5]arene gave the dimeric UIV complex [U(calix[5]arene–4H)(py)]2·4py (3·4py); compound 3 was also formed when no precautions were taken to avoid the presence of traces of water, together with compound 1. The crystal structures of the complexes were determined. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Synthesis, crystal structure and reactivity of uranium(iv) complexes with p-tert-butylcalix[4]arene ligands

Reactions of UCl4 with 25,27-dimethoxy-5,11,17,23-tetra-tert-butylcalix[4]arene (H2Me2calix) in THF or pyridine at 80 degrees C gave [UCl2(Me2calix)L2] [L = THF (1) or pyridine (2)]. Similar treatment of U(acac)(4) (acac = MeCOCHCOMe) with H2Me2calix in THF or pyridine afforded [U(acac)2(Me2calix)] (3). The bis-calixarene compound [U(Me2calix)(H2calix)] (4) was obtained by reaction of U(OTf)4 or U(OTf)3 with H2Me2calix in pyridine at 110 degrees C. Treatment of UCl4 with H2Me2calix in pyridine at 110 degrees C gave [Mepy][UCl2(Hcalix)(py)2] (5) resulting from demethylation and acid cleavage of the methoxy groups of the calixarene ligand of 2. Adventitious traces of air were responsible for the formation of [Hpy][Mepy]4[{UCl(calix)}3(mu3-O)][UCl6] (6) during the reaction of UCl4 and H2Me2calix, and of [{U(Me2calix)(mu3-O)LiCl(THF)}2] (7) during the reaction of 2 with tBuLi. The X-ray crystal structures of 1.2THF, 2.2py, 3.0.25L (L = THF and py), 4.2py, 5, 6.3py and 7.THF have been determined.

Uranium(iv) complexes of calix[n]arenes (n = 4, 6 and 8)

Reaction of UCl4 with calix[n]arenes (n = 4, 6 and 8) in THF or pyridine gave the mononuclear [UCl2(calix[4]arene--2H)(THF)2], bis-binuclear [U2Cl2(calix[6]arene--6H)(THF)3]2 and trinuclear [Hpy]6[U3Cl11(calix[8]arene--7H)] complexes, respectively, which are the first U(IV) complexes of O-unsubstituted calixarenes.

New Efficient Synthesis of [UI4(MeCN)4]. X-ray Crystal Structures of [UI2(MeCN)7][UI6], [UI4(py)3], and [U(dmf)9]I4

Reaction of UCl4 and excess Me3Sil in acetonitrile provides a convenient route to [Ul4(MeCN)4] (1), which was isolated in excellent yield and crystallized in acetonitrile as the ion pair complex [Ul2(MeCN)7][Ul6] (2). Compound 1 was transformed in pyridine (py) and dimethylformamide (dmf) into the Lewis base adducts [Ul4(py)3] (3) and [Ul4(dmf)6] (4). Crystals of 3 and [U(dmf)9]l4 (5) were obtained by slow diffusion of diethyl ether into pyridine or dmf solutions of 1; compound 5 is the first tetracationic {U4+} entity to have been crystallographically characterized.

Homoleptic Tris(dithiolene) and Tetrakis(dithiolene) Complexes of Uranium(IV)

Reaction of UCl4 with 3 or 4 mol equiv of Na2dddt (dddt = 5,6-dihydro-1,4-dithiine-2,3-dithiolate) in THF afforded the first example of a tetrakis(dithiolene) metal compound, [Na4(THF)8U(dddt)4](infinity) (1). The red crystals of 1 are composed of infinite zigzag chains in which Na2(micro-THF)3 fragments ensure the linking of Na2(THF)5U(dddt)4 moieties; the uranium atom is in a dodecahedral environment of eight sulfur atoms. Treatment of UCl4 with 3 mol equiv of Na2dddt in pyridine gave a mixture of tris- and tetrakis(dithiolene) compounds. After addition of 18c6 (18-crown-6), only the tris(dithiolene) complex was obtained and crystallized as orange crystals of [Na(18c6)(py)2]2[U(dddt)3].2py (2.2py) in which the isolated [U(dddt)3]2- anion adopts a slightly distorted trigonal prismatic configuration. A few red crystals of the unsolvated complex 2 and the trinuclear anionic compound [Na(18c6)(py)2]3[Na{U(dddt)3}2] (3) were also obtained along with orange crystals of 2.2py. All the tris(dithiolene) compounds exhibit large folding of the dddt ligand and significant interaction between the C=C double bond and the metal center.

Synthesis and crystal structure of tetra- and hexanuclear uranium(iv) complexes with hexadentate compartmental Schiff-base ligands

Treatment of UCl4 with the hexadentate Schiff bases H2Li in thf gave the expected [ULiCl2(thf)] complexes [H2Li=N,N'-bis(3-methoxysalicylidene)-R and R = 2,2-dimethyl-1,3-propanediamine (i= 1), R = 1,3-propanediamine (i= 2), R = 2-amino-benzylamine (i= 3), R = 2-methyl-1,2-propanediamine (i= 4), R = 1,2-phenylenediamine (i= 5)]. The crystal structure of [UL4Cl2(thf)] (4) shows the metal in a quite perfect pentagonal bipyramidal configuration, with the two Cl atoms in apical positions. Reaction of UCl4 with H4Li in pyridine did not afford the mononuclear products [U(H2Li)Cl2(py)x] but gave instead polynuclear complexes [H4Li=N,N'-bis(3-hydroxysalicylidene)-R and R = 1,3-propanediamine (i= 6), R = 2-amino-benzylamine (i= 7) or R = 2-methyl-1,2-propanediamine (i= 8)]. In the presence of H4L6 and H4L7 in pyridine, UCl4 was transformed in a serendipitous and reproducible manner into the tetranuclear U(iv) complexes [Hpy]2[U4(L6)2(H2L6)2Cl6] (6a) and [Hpy]2[U4(L7)2(H2L7)2Cl6][U4(L7)2(H2L7)2Cl4(py)2] (7), respectively. Treatment of UCl4 with [Zn(H2L6)] led to the formation of the neutral compound [U4(L6)2(H2L6)2Cl4(py)2] (6b). The hexanuclear complex [Hpy]2[U6(L8)4Cl10(py)4] (8) was obtained by reaction of UCl4 and H4L8. The centrosymmetric crystal structures of 6a.2HpyCl.2py, 6b.6py, 7.16py and 8.6py illustrate the potential of Schiff bases as associating ligands for the design of polynuclear assemblies.

Complexes of uranium(iv) with acyclic polyphenoxides resulting from cleavage of homooxacalixarenes

Reaction of UCl4 with homooxacalixarenes in pyridine results in cleavage of the ether bridges upon nucleophilic attack by pyridine, likely assisted by the U(IV) ion. The zwitterionic diphenoxide species bis[5-tert-butyl-2-oxido-3-(1-pyridiniomethyl)-phenyl]methane L1 formed from p-tert-butyltetrahomodioxacalix[4]arene, p-tert-butylhexahomotrioxacalix[6]arene or p-tert-butyloctahomotetraoxacalix[8]arene and the zwitterionic triphenoxide species 4-tert-butyl-2,6-bis[5-tert-butyl-2-oxido-3-(1-pyridiniomethyl)-benzyl]phenolate (L2)− formed from p-tert-butyltetrahomodioxacalix[6]arene give polyphenoxide complexes of U(IV). Coordination of L1 to UCl4 yields the neutral complex [UCl4(L1)] and, on further heating, the cationic [UCl2(L1)2]2+ species, whereas (L2)− gives only the neutral compound [UCl3(L2)]. In these three complexes, the metal atom is in slightly distorted octahedral environments, with bonding to all phenoxide groups. These are the first instances of U(IV) complexes with polyphenoxide ligands, resulting from unprecedented homooxacalixarene cleavage.

Synthesis and X-ray Crystal Structure of a Urana[1]ferrocenophane, the First Tris(1,1‘-ferrocenylene) Metal Compound

Reaction of UCl4 with Li2fc·tmeda (fc = 1,1‘-ferrocenylene, tmeda = tetramethylethylenediamine) gave the tris(1,1‘-ferrocenylene) uranium complex [Li2(py)3U(fc)3] (1) (py = pyridine). X-ray analysis of a pyridine solvate of 1 revealed the propeller type structure of the U(fc)3 fragment, with the planar cyclopentadienyl rings of each fc group being parallel and with U−C and U−Fe bond distances of 2.52(7) and 3.14(2) A, respectively.