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1.
Dr. Joana T. Coutinho Dr. Mauro Perfetti Dr. José J. Baldoví Dr. Maria A. Antunes Philipp P. Hallmen Heiko Bamberger Dr. Iris Crassee Dr. Milan Orlita Prof. Manuel Almeida Prof. Joris van Slageren Dr. Laura C. J. Pereira 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(7):1758-1766
Early actinide ions have large spin-orbit couplings and crystal field interactions, leading to large anisotropies. The success in using actinides as single-molecule magnets has so far been modest, underlining the need for rational strategies. Indeed, the electronic structure of actinide single-molecule magnets and its relation to their magnetic properties remains largely unexplored. A uranium(III) single-molecule magnet, [UIII{SiMe2NPh}3-tacn)(OPPh3)] (tacn=1,4,7-triazacyclononane), has been investigated by means of a combination of magnetic, spectroscopic and theoretical methods to elucidate the origin of its static and dynamic magnetic properties. 相似文献
2.
Activation of SO2 and CO2 by Trivalent Uranium Leading to Sulfite/Dithionite and Carbonate/Oxalate Complexes
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Anna‐Corina Schmidt Frank W. Heinemann Dr. Christos E. Kefalidis Prof. Dr. Laurent Maron Dr. Peter W. Roesky Prof. Dr. Karsten Meyer 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(42):13501-13506
The first sulfite [{((nP,MeArO)3tacn)UIV}2(μ‐κ1:κ2‐SO3)] (tacn=triazacyclononane) and dithionite [{((nP,MeArO)3tacn)UIV}2(μ‐κ2:κ2‐S2O4)] complexes of uranium from reaction with gaseous SO2 have been prepared. Additionally, the reductive activation of CO2 was investigated with respect to the rare oxalate [{((nP,MeArO)3tacn)UIV}2(μ‐κ2:κ2‐C2O4)] formation. This ultimately provides the unique S2O42?/C2O42? and SO32?/CO32? complex pairs. All new complexes were characterized by a combination of single‐crystal X‐ray diffraction, elemental analysis, UV/Vis/NIR electronic absorption, IR vibrational, and 1H NMR spectroscopy, as well as magnetization (VT SQUID) studies. Moreover, density functional theory (DFT) calculations were carried out to gain further insight into the reaction mechanisms. All observations, together with DFT, support the assumption that SO2 and CO2 show similar (dithionite/oxalate) to analogous (sulfite/carbonate) activation behavior with uranium complexes. 相似文献
3.
Radmila Faizova Farzaneh Fadaei‐Tirani Rizlan Bernier‐Latmani Marinella Mazzanti 《Angewandte Chemie (International ed. in English)》2020,59(17):6756-6759
Reduction of uranyl(VI) to UV and to UIV is important in uranium environmental migration and remediation processes. The anaerobic reduction of a uranyl UVI complex supported by a picolinate ligand in both organic and aqueous media is presented. The [UVIO2(dpaea)] complex is readily converted into the cis‐boroxide UIV species via diborane‐mediated reductive functionalization in organic media. Remarkably, in aqueous media the uranyl(VI) complex is rapidly converted, by Na2S2O4, a reductant relevant for chemical remediation processes, into the stable uranyl(V) analogue, which is then slowly reduced to yield a water‐insoluble trinuclear UIV oxo‐hydroxo cluster. This report provides the first example of direct conversion of a uranyl(VI) compound into a well‐defined molecular UIV species in aqueous conditions. 相似文献
4.
Conrad A. P. Goodwin Dr. Floriana Tuna Prof. Eric J. L. McInnes Prof. Stephen T. Liddle Dr. Jonathan McMaster Dr. Inigo J. Vitorica‐Yrezabal Dr. David P. Mills 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(45):14579-14583
We report the synthesis and characterization of the uranium(III) triamide complex [UIII(N**)3] [ 1 , N**=N(SiMe2tBu)2?]. Surprisingly, complex 1 exhibits a trigonal planar geometry in the solid state, which is unprecedented for three‐coordinate actinide complexes that have exclusively adopted trigonal pyramidal geometries to date. The characterization data for [UIII(N**)3] were compared with the prototypical trigonal pyramidal uranium(III) triamide complex [UIII(N“)3] (N”=N(SiMe3)2?), and taken together with theoretical calculations it was concluded that pyramidalization results in net stabilization for [UIII(N“)3], but this can be overcome with very sterically demanding ligands, such as N**. The planarity of 1 leads to favorable magnetic dynamics, which may be considered in the future design of UIII single‐molecule magnets. 相似文献
5.
Lanhua Chen Dr. Tao Zheng Dr. Songsong Bao Dr. Linjuan Zhang Hsin‐Kuan Liu Prof. Limin Zheng Prof. Jianqiang Wang Yaxing Wang Prof. Juan Diwu Prof. Zhifang Chai Prof. Thomas E. Albrecht‐Schmitt Prof. Shuao Wang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(34):11954-11957
It is shown that UVO2+ ions can reside at UVIO22+ lattice sites during mild reduction and crystallization process under solvothermal conditions, yielding a complicated and rare mixed‐valent uranium phosphonate compound that simultaneously contains UIV, UV, and UVI. The presence of uranium with three oxidation states was confirmed by various characterization techniques, including X‐ray crystallography, X‐ray photoelectron, electron paramagnetic resonance, FTIR, UV/Vis‐NIR absorption, and synchrotron radiation X‐ray absorption spectroscopy, and magnetism measurements. 相似文献
6.
Christopher J. Hoerger Frank W. Heinemann Elisa Louyriac Massimo Rigo Laurent Maron Hansjrg Grützmacher Matthias Driess Karsten Meyer 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(6):1693-1697
Reaction of the trivalent uranium complex [((Ad,MeArO)3N)U(DME)] with one molar equiv [Na(OCAs)(dioxane)3], in the presence of 2.2.2‐crypt, yields [Na(2.2.2‐crypt)][{((Ad,MeArO)3N)UIV(THF)}(μ‐O){((Ad,MeArO)3N)UIV(CAs)}] ( 1 ), the first example of a coordinated η1‐cyaarside ligand (CAs?). Formation of the terminal CAs? is promoted by the highly reducing, oxophilic UIII precursor [((Ad,MeArO)3N)U(DME)] and proceeds through reductive C?O bond cleavage of the bound arsaethynolate anion, OCAs?. If two equiv of OCAs? react with the UIII precursor, the binuclear, μ‐oxo‐bridged U2IV/IV complex [Na(2.2.2‐crypt)]2[{((Ad,MeArO)3N)UIV}2(μ‐O)(μ‐AsCAs)] ( 2 ), comprising the hitherto unknown μ:η1,η1‐coordinated (AsCAs)2? ligand, is isolated. The mechanistic pathway to 2 involves the decarbonylation of a dimeric intermediate formed in the reaction of 1 with OCAs?. An alternative pathway to complex 2 is by conversion of 1 via addition of one further equiv of OCAs?. 相似文献
7.
Kasper S. Pedersen Katie R. Meihaus Andrei Rogalev Fabrice Wilhelm Daniel Aravena Martín Amoza Eliseo Ruiz Jeffrey R. Long Jesper Bendix Rodolphe Clrac 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(44):15797-15801
The first structurally characterized hexafluorido complex of a tetravalent actinide ion, the [UF6]2? anion, is reported in the (NEt4)2[UF6]?2 H2O salt ( 1 ). The weak magnetic response of 1 results from both UIV spin and orbital contributions, as established by combining X‐ray magnetic circular dichroism (XMCD) spectroscopy and bulk magnetization measurements. The spin and orbital moments are virtually identical in magnitude, but opposite in sign, resulting in an almost perfect cancellation, which is corroborated by ab initio calculations. This work constitutes the first experimental demonstration of a seemingly non‐magnetic molecular actinide complex carrying sizable spin and orbital magnetic moments. 相似文献
8.
Radmila Faizova Dr. Farzaneh Fadaei-Tirani Prof. Dr. Rizlan Bernier-Latmani Prof. Dr. Marinella Mazzanti 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(17):6822-6825
Reduction of uranyl(VI) to UV and to UIV is important in uranium environmental migration and remediation processes. The anaerobic reduction of a uranyl UVI complex supported by a picolinate ligand in both organic and aqueous media is presented. The [UVIO2(dpaea)] complex is readily converted into the cis-boroxide UIV species via diborane-mediated reductive functionalization in organic media. Remarkably, in aqueous media the uranyl(VI) complex is rapidly converted, by Na2S2O4, a reductant relevant for chemical remediation processes, into the stable uranyl(V) analogue, which is then slowly reduced to yield a water-insoluble trinuclear UIV oxo-hydroxo cluster. This report provides the first example of direct conversion of a uranyl(VI) compound into a well-defined molecular UIV species in aqueous conditions. 相似文献
9.
Dr. Erli Lu Dr. Ashley J. Wooles Dr. Matthew Gregson Philip J. Cobb Prof. Stephen T. Liddle 《Angewandte Chemie (International ed. in English)》2018,57(22):6587-6591
Reaction of [U{C(SiMe3)(PPh2)}(BIPM)(μ‐Cl)Li(TMEDA)(μ‐TMEDA)0.5]2 (BIPM=C(PPh2NSiMe3)2; TMEDA=Me2NCH2CH2NMe2) with [Rh(μ‐Cl)(COD)]2 (COD=cyclooctadiene) affords the heterotrimetallic UIV?RhI2 complex [U(Cl)2{C(PPh2NSiMe3)(PPh[C6H4]NSiMe3)}{Rh(COD)}{Rh(CH(SiMe3)(PPh2)}]. This complex has a very short uranium–rhodium distance, the shortest uranium–rhodium bond on record and the shortest actinide–transition metal bond in terms of formal shortness ratio. Quantum‐chemical calculations reveal a remarkable Rh UIV net double dative bond interaction, involving RhI 4d ‐ and 4dxy/xz‐type donation into vacant UIV 5f orbitals, resulting in a Wiberg/Nalewajski–Mrozek U?Rh bond order of 1.30/1.44, respectively. Despite being, formally, purely dative, the uranium–rhodium bonding interaction is the most substantial actinide–metal multiple bond yet prepared under conventional experimental conditions, as confirmed by structural, magnetic, and computational analyses. 相似文献
10.
Spectroscopic,Electrochemical and Computational Characterisation of Ru Species Involved in Catalytic Water Oxidation: Evidence for a [RuV(O)(Py2Metacn)] Intermediate
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Carla Casadevall Dr. Zoel Codolà Prof. Dr. Miquel Costas Prof. Dr. Julio Lloret‐Fillol 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(29):10111-10126
A new family of ruthenium complexes based on the N‐pentadentate ligand Py2Metacn (N‐methyl‐N′,N′′‐bis(2‐picolyl)‐1,4,7‐triazacyclononane) has been synthesised and its catalytic activity has been studied in the water‐oxidation (WO) reaction. We have used chemical oxidants (ceric ammonium nitrate and NaIO4) to generate the WO intermediates [RuII(OH2)(Py2Metacn)]2+, [RuIII(OH2)(Py2Metacn)]3+, [RuIII(OH)(Py2Metacn)]2+ and [RuIV(O)(Py2Metacn)]2+, which have been characterised spectroscopically. Their relative redox and pH stability in water has been studied by using UV/Vis and NMR spectroscopies, HRMS and spectroelectrochemistry. [RuIV(O)(Py2Metacn)]2+ has a long half‐life (>48 h) in water. The catalytic cycle of WO has been elucidated by using kinetic, spectroscopic, 18O‐labelling and theoretical studies, and the conclusion is that the rate‐determining step is a single‐site water nucleophilic attack on a metal‐oxo species. Moreover, [RuIV(O)(Py2Metacn)]2+ is proposed to be the resting state under catalytic conditions. By monitoring CeIV consumption, we found that the O2 evolution rate is redox‐controlled and independent of the initial concentration of CeIV. Based on these facts, we propose herein that [RuIV(O)(Py2Metacn)]2+ is oxidised to [RuV(O)(Py2Metacn)]2+ prior to attack by a water molecule to give [RuIII(OOH)(Py2Metacn)]2+. Finally, it is shown that the difference in WO reactivity between the homologous iron and ruthenium [M(OH2)(Py2Metacn)]2+ (M=Ru, Fe) complexes is due to the difference in the redox stability of the key MV(O) intermediate. These results contribute to a better understanding of the WO mechanism and the differences between iron and ruthenium complexes in WO reactions. 相似文献
11.
Clément Camp Victor Mougel Dr. Jacques Pécaut Prof. Laurent Maron Dr. Marinella Mazzanti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(51):17528-17540
Two new arene inverted‐sandwich complexes of uranium supported by siloxide ancillary ligands [K{U(OSi(OtBu)3)3}2(μ‐η6:η6‐C7H8)] ( 3 ) and [K2{U(OSi(OtBu)3)3}2(μ‐η6:η6‐C7H8)] ( 4 ) were synthesized by the reduction of the parent arene‐bridged complex [{U(OSi(OtBu)3)3}2(μ‐η6:η6‐C7H8)] ( 2 ) with stoichiometric amounts of KC8 yielding a rare family of inverted‐sandwich complexes in three states of charge. The structural data and computational studies of the electronic structure are in agreement with the presence of high‐valent uranium centers bridged by a reduced tetra‐anionic toluene with the best formulation being UV–(arene4?)–UV, KUIV–(arene4?)–UV, and K2UIV–(arene4?)–UIV for complexes 2 , 3 , and 4 respectively. The potassium cations in complexes 3 and 4 are coordinated to the siloxide ligands both in the solid state and in solution. The addition of KOTf (OTf=triflate) to the neutral compound 2 promotes its disproportionation to yield complexes 3 and 4 (depending on the stoichiometry) and the UIV mononuclear complex [U(OSi(OtBu)3)3(OTf)(thf)2] ( 5 ). This unprecedented reactivity demonstrates the key role of potassium for the stability of these complexes. 相似文献
12.
Dieuwertje K. Modder Chad T. Palumbo Iskander Douair Rosario Scopelliti Laurent Maron Marinella Mazzanti 《Chemical science》2021,12(17):6153
The redox chemistry of uranium is dominated by single electron transfer reactions while single metal four-electron transfers remain unknown in f-element chemistry. Here we show that the oxo bridged diuranium(iii) complex [K(2.2.2-cryptand)]2[{((Me3Si)2N)3U}2(μ-O)], 1, effects the two-electron reduction of diphenylacetylene and the four-electron reduction of azobenzene through a masked U(ii) intermediate affording a stable metallacyclopropene complex of uranium(iv), [K(2.2.2-cryptand)][U(η2-C2Ph2){N(SiMe3)2}3], 3, and a bis(imido)uranium(vi) complex [K(2.2.2-cryptand)][U(NPh)2{N(SiMe3)2}3], 4, respectively. The same reactivity is observed for the previously reported U(ii) complex [K(2.2.2-cryptand)][U{N(SiMe3)2}3], 2. Computational studies indicate that the four-electron reduction of azobenzene occurs at a single U(ii) centre via two consecutive two-electron transfers and involves the formation of a U(iv) hydrazide intermediate. The isolation of the cis-hydrazide intermediate [K(2.2.2-cryptand)][U(N2Ph2){N(SiMe3)2}3], 5, corroborated the mechanism proposed for the formation of the U(vi) bis(imido) complex. The reduction of azobenzene by U(ii) provided the first example of a “clear-cut” single metal four-electron transfer in f-element chemistry.Both a masked and the actual complex [U(ii){N(SiMe3)2}3]+ effect the reduction of azobenzene to yield a U(vi) bis-imido species providing the first example of a “clear-cut” metal centred four-electron reduction in f-element chemistry. 相似文献
13.
Investigation of Uranium Tris(imido) Complexes: Synthesis,Characterization, and Reduction Chemistry of [U(NDIPP)3(thf)3]
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Nickolas H. Anderson Haolin Yin John J. Kiernicki Dr. Phillip E. Fanwick Prof. Eric J. Schelter Prof. Suzanne C. Bart 《Angewandte Chemie (International ed. in English)》2015,54(32):9386-9389
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 UV 5f 1 centers, with no antiferromagnetic coupling present. Characterization of these complexes was accomplished using single‐crystal X‐ray diffraction, variable‐temperature 1H NMR spectroscopy, as well as IR and UV/Vis absorption spectroscopic studies. 相似文献
14.
Nickolas H. Anderson Haolin Yin John J. Kiernicki Phillip E. Fanwick Eric J. Schelter Suzanne C. Bart 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(32):9518-9521
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 UV 5f 1 centers, with no antiferromagnetic coupling present. Characterization of these complexes was accomplished using single‐crystal X‐ray diffraction, variable‐temperature 1H NMR spectroscopy, as well as IR and UV/Vis absorption spectroscopic studies. 相似文献
15.
On Approaching the Limit of Molecular Magnetic Anisotropy: A Near‐Perfect Pentagonal Bipyramidal Dysprosium(III) Single‐Molecule Magnet
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You‐Song Ding Dr. Nicholas F. Chilton Prof. Dr. Richard E. P. Winpenny Prof. Dr. Yan‐Zhen Zheng 《Angewandte Chemie (International ed. in English)》2016,55(52):16071-16074
We report a monometallic dysprosium complex, [Dy(OtBu)2(py)5][BPh4] ( 5 ), that shows the largest effective energy barrier to magnetic relaxation of Ueff=1815(1) K. The massive magnetic anisotropy is due to bis‐trans‐disposed tert‐butoxide ligands with weak equatorial pyridine donors, approaching proposed schemes for high‐temperature single‐molecule magnets (SMMs). The blocking temperature, TB , is 14 K, defined by zero‐field‐cooled magnetization experiments, and is the largest for any monometallic complex and equal with the current record for [Tb2N2{N(SiMe3)2}4(THF)2]. 相似文献
16.
Subtle Interactions and Electron Transfer between UIII,NpIII, or PuIII and Uranyl Mediated by the Oxo Group
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Prof. Polly L. Arnold Michał S. Dutkiewicz Dr. Markus Zegke Dr. Olaf Walter Dr. Christos Apostolidis Dr. Emmalina Hollis Dr. Anne‐Fréderique Pécharman Dr. Nicola Magnani Dr. Jean‐Christophe Griveau Dr. Eric Colineau Prof. Roberto Caciuffo Xiaobin Zhang Prof. Georg Schreckenbach Prof. Jason B. Love 《Angewandte Chemie (International ed. in English)》2016,55(41):12797-12801
A dramatic difference in the ability of the reducing AnIII center in AnCp3 (An=U, Np, Pu; Cp=C5H5) to oxo‐bind and reduce the uranyl(VI) dication in the complex [(UO2)(THF)(H2L)] (L=“Pacman” Schiff‐base polypyrrolic macrocycle), is found and explained. These are the first selective functionalizations of the uranyl oxo by another actinide cation. At‐first contradictory electronic structural data are explained by combining theory and experiment. Complete one‐electron transfer from Cp3U forms the UIV‐uranyl(V) compound that behaves as a UV‐localized single molecule magnet below 4 K. The extent of reduction by the Cp3Np group upon oxo‐coordination is much less, with a NpIII‐uranyl(VI) dative bond assigned. Solution NMR and NIR spectroscopy suggest NpIVUV but single‐crystal X‐ray diffraction and SQUID magnetometry suggest a NpIII‐UVI assignment. DFT‐calculated Hirshfeld charge and spin density analyses suggest half an electron has transferred, and these explain the strongly shifted NMR spectra by spin density contributions at the hydrogen nuclei. The PuIII–UVI interaction is too weak to be observed in THF solvent, in agreement with calculated predictions. 相似文献
17.
Synthesis,Crystal Structure and Magnetic Properties of a Novel Heterobimetallic Rhenium(IV)–Dysprosium(III) Chain
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Carolina Pejo Dr. Guilherme P. Guedes Prof. Miguel A. Novak Dr. Nivaldo L. Speziali Dr. Raúl Chiozzone Prof. Miguel Julve Prof. Francesc Lloret Dr. Maria G. F. Vaz Dr. Ricardo González 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(24):8696-8700
The use of the mononuclear rhenium(IV) precursor [ReBr5(H2pydc)]? (H2pydc=3,5‐pyridinedicarboxylic acid) as a metalloligand towards dysprosium(III) afforded the first heterobimetallic ReIV–DyIII complex. Crystal structures and static and dynamic magnetic properties of both rhenium‐containing species are reported herein. The 5d–4f compound shows an extended 1D structure and the AC magnetic measurements reveal frequency dependence at low temperature suggesting slow relaxation of the magnetization. 相似文献
18.
Polly L. Arnold Micha S. Dutkiewicz Markus Zegke Olaf Walter Christos Apostolidis Emmalina Hollis Anne‐Frderique Pcharman Nicola Magnani Jean‐Christophe Griveau Eric Colineau Roberto Caciuffo Xiaobin Zhang Georg Schreckenbach Jason B. Love 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(41):12989-12993
A dramatic difference in the ability of the reducing AnIII center in AnCp3 (An=U, Np, Pu; Cp=C5H5) to oxo‐bind and reduce the uranyl(VI) dication in the complex [(UO2)(THF)(H2L)] (L=“Pacman” Schiff‐base polypyrrolic macrocycle), is found and explained. These are the first selective functionalizations of the uranyl oxo by another actinide cation. At‐first contradictory electronic structural data are explained by combining theory and experiment. Complete one‐electron transfer from Cp3U forms the UIV‐uranyl(V) compound that behaves as a UV‐localized single molecule magnet below 4 K. The extent of reduction by the Cp3Np group upon oxo‐coordination is much less, with a NpIII‐uranyl(VI) dative bond assigned. Solution NMR and NIR spectroscopy suggest NpIVUV but single‐crystal X‐ray diffraction and SQUID magnetometry suggest a NpIII‐UVI assignment. DFT‐calculated Hirshfeld charge and spin density analyses suggest half an electron has transferred, and these explain the strongly shifted NMR spectra by spin density contributions at the hydrogen nuclei. The PuIII–UVI interaction is too weak to be observed in THF solvent, in agreement with calculated predictions. 相似文献
19.
C. Crăciun D. Rusu L. Pop-Fanea M. Hossu M. Rusu L. David 《Journal of Radioanalytical and Nuclear Chemistry》2005,264(3):589-594
Summary Six sandwich-type uranium(IV)-polyoxometalates (UIV-POM) were prepared and investigated by FT-IR and UV-VIS spectroscopy. Changes in position and shape of antisymmetric stretching vibration bands in the 640-1000 cm-1 region were identified in all UIV-POM FT-IR spectra. These changes are related to coordination of U(IV) to the trilacunary Keggin units. Visible electronic spectra of aqueous solutions of UIV-POM complexes correspond to uranium 3H4 electronic ground state, having a quasicubic configuration. Presence of electronic transitions were identified by UV spectroscopy of UIV-POM complexes in aqueous solutions. 相似文献
20.
Expanding the Chemistry of Molecular U2+ Complexes: Synthesis,Characterization, and Reactivity of the {[C5H3(SiMe3)2]3U}− Anion
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Cory J. Windorff Dr. Matthew R. MacDonald Dr. Katie R. Meihaus Dr. Joseph W. Ziller Prof. Jeffrey R. Long Prof. William J. Evans 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(2):772-782
The synthesis of new molecular complexes of U2+ has been pursued to make comparisons in structure, physical properties, and reactivity with the first U2+ complex, [K(2.2.2‐cryptand)][Cp′3U], 1 (Cp′=C5H4SiMe3). Reduction of Cp′′3U [Cp′′=C5H3(SiMe3)2] with KC8 in the presence of 2.2.2‐cryptand or 18‐crown‐6 generates [K(2.2.2‐cryptand)][Cp′′3U], 2‐K(crypt) , or [K(18‐crown‐6)(THF)2][Cp′′3U], 2‐K(18c6) , respectively. The UV/Vis spectra of 2‐K and 1 are similar, and they are much more intense than those of U3+ analogues. Variable temperature magnetic susceptibility data for 1 and 2‐K(crypt) reveal lower room temperature χMT values relative to the experimental values for the 5f3 U3+ precursors. Stability studies monitored by UV/Vis spectroscopy show that 2‐K(crypt) and 2‐K(18c6) have t1/2 values of 20 and 15 h at room temperature, respectively, vs. 1.5 h for 1 . Complex 2‐K(18c6) reacts with H2 or PhSiH3 to form the uranium hydride, [K(18‐crown‐6)(THF)2][Cp′′3UH], 3 . Complexes 1 and 2‐K(18c6) both reduce cyclooctatetraene to form uranocene, (C8H8)2U, as well as the U3+ byproducts [K(2.2.2‐cryptand)][Cp′4U], 4 , and Cp′′3U, respectively. 相似文献