Carbon Dioxide Activation with Sterically Pressured Mid- and High-Valent Uranium Complexes

Bart, Suzanne C.; Anthon, Christian; Heinemann, Frank W.; Bill, Eckhard; Edelstein, Norman M.; Meyer, Karsten

doi:10.1021/ja804263w

Cited by 234 publications

(275 citation statements)

References 59 publications

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“…11). 58 Along with the generation of the thermodynamically stable mesityl isocyanate, the authors 2S attribute the reactivity of these imido complexes to unfavorable steric congestion preventing optimal coordination of the bulky mesityl imido ligand -the U=N-C angle observed in the molecular structure of 52 is substantially less-linear (154.7(8)") than that for the SiMeJ variant 50 (U=N-Si = 30 173.7(3)"), thus resulting in a more energized molecular fragment (weaker U=N bond), which readily undergoes reaction . …”

Section: -Electron Oxidation Of Trivalent Uraniummentioning

confidence: 99%

Pentavalent uranium chemistry—synthetic pursuit of a rare oxidation state

2009

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Section: -Electron Oxidation Of Trivalent Uraniummentioning

confidence: 99%

Pentavalent uranium chemistry—synthetic pursuit of a rare oxidation state

2009

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“…Over the past several years, a number of U(IV) [1][2][3][4][5][6], U(V) [7][8][9][10][11][12][13], and U(VI) [1,2,9,10,[14][15][16][17][18], imido complexes have been prepared and characterized. In particular, the U(VI) bis(imido) complexes, typified by compounds such as U(N t Bu) 2 I 2 (THF) 2 , are isoelectronic with UO 2 2+ and are known to contain more covalent multiple bonds than those in the uranyl ion [17].…”

Section: Introductionmentioning

confidence: 99%

[2 + 2] cycloaddition reactions at terminal imido uranium(IV) complexes to yield isolable cycloadducts

Jilek

Tomson

Scott

et al. 2014

Inorganica Chimica Acta

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“…[5] Temperature-dependent magnetic data were collected in the temperature range 2-300 K. At 300 K, 4 displays an effective magnetic moment of 1.96 m B per uranium ion, which is lower that the theoretical value calculated for the free f 1 ion in the L-S coupling scheme (m eff = 2.54 m B ), but within the range of values reported for U V compounds. [32,33] The plot of c versus T (Figure 3) clearly indicates the presence of an unambiguous antiferromagnetic coupling [6] between the f 1 ions, with a maximum at 6 K. Unambiguous evidence of magnetic communication between uranium centers is limited to three examples of dimeric complexes, which include the [{UO 2 (dbm) 2 K(18C6)} 2 ] dimer. [6,8,34] This is the first example of tetranuclear complex that shows unambiguous magnetic coupling, although the presence of magnetic coupling at temperature lower than 2 K had been suspected for 1.…”

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confidence: 99%

Stable Pentavalent Uranyl Species and Selective Assembly of a Polymetallic Mixed‐Valent Uranyl Complex by Cation–Cation Interactions

et al. 2009

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Cation-cation interactions are a key feature of actinide chemistry. These interactions can be used in two areas that currently attract great interest, namely the expansion of felement supramolecular chemistry and the enhancement of magnetic interactions in actinide compounds. [1][2][3][4][5][6][7][8][9][10][11][12] Moreover, oligomeric cation-cation species that present mutually coordinated actinyl ions are likely to play a crucial role in nuclear waste reprocessing and in the migration of radioactive actinides in the environment. [1] Cation-cation interactions are known to be important in neptunyl(V) structural chemistry, [13] but are more rarely found in uranyl(VI) compounds because of the lower basicity of the UO 2 2+ oxygen atoms. Dimeric compounds formed through the mutual binding of pentavalent uranyl(V) ions have been proposed as intermediates in the disproportionation of pentavalent uranyl ions to UO 2 2+ and U IV species.[14]As a result, bulky ligands have been used in the past few years to disfavor cation-cation interactions and allow the synthesis of rare UO 2 + complexes, [15][16][17][18][19][20][21] which have been the subject of two recent reviews.[ [8] The presence of antiferromagnetic coupling between the oxo-bridged uranium centers was unambiguously demonstrated for the dimetallic complex but is less evident for the tetrametallic complex. [8] The decomposition of these polymetallic complexes of pentavalent uranyl ions to UO 2 2+ and U IV species starts rapidly after dissolution in organic solvents and is accelerated by traces of water. From these reactivity studies, it occurred to us that the stability of these polymeric systems could possibly be modulated by fine-tuning the electronic and steric properties of the ligand and coordinating cation. Herein, we report the first example of a UO 2 + ···UO 2 + complex that is highly stable in organic solvents and, significantly, is stable toward hydrolysis. We also describe the selective synthesis and the structure of the first mixed-valent UO 2 + ···UO 2 2+ molecular complex, which provides a rare example of functionalization of the U VI =O group. [20,22] By breaking away from the current trend of using steric bulk to prevent dimer formation and the associated disproportionation of UO 2 + complexes, we show that the non-bulky Schiff base ligand salen 2À (N,N'-bis(salicylidene)ethylenediamine) can stabilize pentavalent uranyl ions through the formation of a highly stable cation-cation complex. Moreover, we demonstrate that the resulting tetrameric uranyl(V) complex exhibits unambiguous antiferromagnetic coupling between the uranium centers.The reaction of the recently reported UO 2 + complex [(UO 2 Py 5 )(KI 2 Py 2 )] n (2; Py = pyridine) [23] with salenK 2 in pyridine led to the formation of the complex of pentavalent uranyl 3 as a violet powder that was insoluble in pyridine. The elemental analysis of 3 indicates the presence of a complex of general formula [(UO 2 )(salen)K(Py)]·1.4 KI, which most likely has a solid-state polymeric structure. Compound ...

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Carbon Dioxide Activation with Sterically Pressured Mid- and High-Valent Uranium Complexes

Cited by 234 publications

References 59 publications

Pentavalent uranium chemistry—synthetic pursuit of a rare oxidation state

Pentavalent uranium chemistry—synthetic pursuit of a rare oxidation state

[2 + 2] cycloaddition reactions at terminal imido uranium(IV) complexes to yield isolable cycloadducts

Stable Pentavalent Uranyl Species and Selective Assembly of a Polymetallic Mixed‐Valent Uranyl Complex by Cation–Cation Interactions

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