- Reversible binding and reduction of dinitrogen by a uranium(III) pentalene complex
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The U(III) mixed-sandwich compound [U(η-Cp*)(η-C8H4{SiiPr3-1,4}2)] 1 may be prepared by sequential reaction of UI3 with KCp* followed by K2[C8H4{SiiPr3-1,4}2], and has been crystallographically characterized. 1 reacts reversibly with dinitrogen to afford dimeric [{U(η-Cp*)(η-C8H4{SiiPr3-1,4}2)}2(μ-η2:η2-N2)] 2 , whose X-ray crystal structure reveals a sideways-bound, bridging diazenido (N22-) ligand. Copyright
- Cloke, F. Geoffrey N.,Hitchcock, Peter B.
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- Facile syntheses of unsolvated Ul3 and tetramethylcyclopentadienyl uranium halides
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In the course of comparing the reaction chemistry of (C5Me 5)3U, 1, and its slightly less crowded analogue (C 5Me5H)3U, 2, new syntheses of Ul3, (C5Me4H)3U, (C5Me4H) 3UCl, 3, and (C5Me5)3UCl, 4, have been developed. Additionally, (C5Me5H)3Ul, 5, and (C5Me4H)2UCl2, 6, have been identified for the first time. A facile synthesis of unsolvated Ul3 is reported that proceeds in high yield with inexpensive equipment from iodine and hot uranium turnings. Both Ul3 and Ul3(THF) 4 react with KC5Me4H in toluene to make unsolvated C5Me4H)3U in higher yield than in previous reports that involve reduction of tetravalent (C5Me 4H)3UCl, 3. A more atom-efficient synthesis of complex 3 is also reported that proceeds from reduction of t-BuCl, PhCl, or HgCl 2 by 2. Similarly, (C5Me4H)3U reacts with Phi or Hgl2 to generate (C5Me4H) 3Ul. These studies also provided a basis to improve the synthesis of (C5Me5)3UCl from 1 by employing t-BuCl or HgCl2 as the halide source. Like (C5Me5)UCl, the (C5Me4H)3UCl complex reacts with HgCl 2 to form (C5Me5H)2 and (C 5Me4H)2UCl2, 6, but unlike (C 5Me5)3UX (X = Cl or l), the less substituted (C5Me4H)3UX complexes do not reduce t-BuCl or PhX. The synthesis of 6 from (C5Me4H)MgCl·THF and UCl4 is also included.
- Evans, William J.,Kozimor, Stosh A.,Ziller, Joseph W.,Fagin, Anatolii A.,Bochkarev, Mikhail N.
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- The distinct affinity of cyclopentadienyl ligands towards trivalent uranium over lanthanide ions. Evidence for cooperative ligation and back-bonding in the actinide complexes
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The mono and bis(cyclopentadienyl) compounds [M(C5H 4But)I2] and [M(C5H 4But)2I] (M = U, La, Ce, Nd) were formed in thf by comproportionation reactions of [M(C5H4Bu t)3] and LnI3 or [UI3(L) 4] (L = thf or py) in the molar ratio of 1 : 2 and 2 : 1, respectively, while treatment of [UI3(py)4] or LnI 3 (Ln = La, Ce, Nd) with 1 or 2 mol equivalents of LiC 5H4But in thf afforded the [M(C 5H4But)I2] and [M(C 5H4But)2I2]- compounds, respectively. The X-ray crystal structures of [M(C5H 4But)I2(py)3] (M = U, La, Ce, Nd), [{Ce(C5H4But)2(μ-I)}2] and [M(C5H4But)2I(py)2] (M = U, Nd) have been determined; the differences between the average M-C distances in the mono(cyclopentadienyl) complexes correspond to the variation in the ionic radii of the trivalent uranium and lanthanide ions while the U-N and U-I bond lengths seem to be smaller than those predicted from a purely ionic bonding model. The distinct affinity of the cyclopentadienyl ligands towards Ln(III) and U(III) was revealed by two series of competing reactions: the ligand exchange reactions between [Ln(C5H4Bu t)n′I3-n′] (Ln = La, Ce, Nd) and [U(C5H4But)n′I 3-n′] species (1 ≤ n′ + n′ = n ≤ 5), and the addition of n mol equivalents of LiC5H4But (1 ≤ n ≤ 5) to a 1: 1 mixture of LnI3 and [UI 3(thf)4] or [UI3(py)4]. The stability of the [M(C5H4But)I2] species was found to vary in the order Nd > Ce > U > La, a trend which is in accord with an electrostatic bonding model. However, the bis and tris(cyclopentadienyl) complexes of uranium are more stable than their lanthanide analogues. This difference can be accounted for by a higher degree of covalency in the U-C5H4But bond, resulting from the late appearance of back-bonding which would emerge only after the first cyclopentadienyl ligand is bound. The Royal Society of Chemistry 2005.
- Mehdoui, Thouraya,Berthet, Jean-Claude,Thuery, Pierre,Ephritikhine, Michel
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- Synthesis and structural characterisation of lanthanide and actinide phosphaorganometallic complexes derived from the 3,5-di-tert-butyl-1,2,4-triphospholyl ring anion, P3C2But-2: Crystal and molecular structures
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Full title. Synthesis and structural characterisation of lanthanide and actinide phosphaorganometallic complexes derived from the 3,5-di-tert-butyl-1,2,4-triphospholyl ring anion, P3C2But-2: Crystal and molecula
- Clentsmith, Guy K.B.,Cloke, F. Geoffrey N.,Francis, Matthew D.,Hanks, John R.,Hitchcock, Peter B.,Nixon, John F.
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p. 2287 - 2292
(2008/09/21)
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- Low-valent uranium iodides: Straightforward solution syntheses of UI 3 and UI4 etherates
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Uranium turnings react with elemental iodine in diethyl ether at room temperature, with sonication and/or stirring, over a period of days to afford UI3, UI4(OEt2)2, or UI 4(OBun2) depending on the stoichiometry or ether solvent. This is the first room temperature, and thus safe and convenient, synthesis of UI3.
- Carmichael, Christopher D.,Jones, Natalie A.,Arnold, Polly L.
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p. 8577 - 8579
(2009/04/12)
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- Studies on ABX6 Compounds. IV[4] The Structures of AUI6 Compounds (A: Sr, Eu, Ba)
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The compounds SrUI6, EuUI6 and BaUI6 are synthesized for the first time.Their crystal structures are isotypic, and they can be described as ord ered substitution variants of the AlCl3 type.
- Beck, H. P.,Kuehn, F.
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