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81.
Synthesis and Characterization of a Cu14 Hydride Cluster Supported by Neutral Donor Ligands 下载免费PDF全文
Thuy‐Ai D. Nguyen Bryan R. Goldsmith Homaira T. Zaman Dr. Guang Wu Prof. Dr. Baron Peters Prof. Dr. Trevor W. Hayton 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(14):5341-5344
The copper hydride clusters [Cu14H12(phen)6(PPh3)4][X]2 (X=Cl or OTf; OTf=trifluoromethanesulfonate, phen=1,10‐phenanthroline) are obtained in good yields by the reaction of [(Ph3P)CuH]6 with phen, in the presence of a halide or pseudohalide source. The complex [Cu14H12(phen)6(PPh3)4][Cl]2 reacts with CO2 in CH2Cl2, in the presence of excess Ph3P, to form the formate complex [(Ph3P)2Cu(κ2‐O2CH)], along with [(phen)(Ph3P)CuCl]. 相似文献
82.
Liane M. Moreau Alexandre Herve Mark D. Straub Dominic R. Russo Rebecca J. Abergel Selim Alayoglu John Arnold Augustin Braun Gauthier J. P. Deblonde Yangdongling Liu Trevor D. Lohrey Daniel T. Olive Yusen Qiao Julian A. Rees David K. Shuh Simon J. Teat Corwin H. Booth Stefan G. Minasian 《Chemical science》2020,11(18):4648
We report the structural properties of ultra-small ThO2 and UO2 nanoparticles (NPs), which were synthesized without strong binding surface ligands by employing a covalent organic framework (COF-5) as an inert template. The resultant NPs were used to observe how structural properties are affected by decreasing grain size within bulk actinide oxides, which has implications for understanding the behavior of nuclear fuel materials. Through a comprehensive characterization strategy, we gain insight regarding how structure at the NP surface differs from the interior. Characterization using electron microscopy and small-angle X-ray scattering indicates that growth of the ThO2 and UO2 NPs was confined by the pores of the COF template, resulting in sub-3 nm particles. X-ray absorption fine structure spectroscopy results indicate that the NPs are best described as ThO2 and UO2 materials with unpassivated surfaces. The surface layers of these particles compensate for high surface energy by exhibiting a broader distribution of Th–O and U–O bond distances despite retaining average bond lengths that are characteristic of bulk ThO2 and UO2. The combined synthesis and physical characterization efforts provide a detailed picture of actinide oxide structure at the nanoscale, which remains highly underexplored compared to transition metal counterparts.ThO2 and UO2 nanoparticles synthesized using a COF-5 template exhibit unpassivated surfaces and provide insight into nanoscale properties of actinides. 相似文献
83.
Reichhardt C Uchida M O'Neil A Li R Prevelige PE Douglas T 《Chemical communications (Cambridge, England)》2011,47(22):6326-6328
Biomimetic chemistry offers new approaches to supramolecular materials synthesis and assembly. We have demonstrated that an assembled viral protein cage, comprising an organic core-shell structure, can be used as a template for the size constrained synthesis of Fe(2)O(3). Particle nucleation is directed by the inner scaffold protein layer, while the size constraints are determined by the outer capsid layer. 相似文献
84.
Fortier S Walensky JR Wu G Hayton TW 《Journal of the American Chemical Society》2011,133(30):11732-11743
Oxidation of [Li(DME)(3)][U(CH(2)SiMe(3))(5)] with 0.5 equiv of I(2), followed by immediate addition of LiCH(2)SiMe(3), affords the high-valent homoleptic U(V) alkyl complex [Li(THF)(4)][U(CH(2)SiMe(3))(6)] (1) in 82% yield. In the solid-state, 1 adopts an octahedral geometry as shown by X-ray crystallographic analysis. Addition of 2 equiv of tert-butanol to [Li(DME)(3)][U(CH(2)SiMe(3))(5)] generates the heteroleptic U(IV) complex [Li(DME)(3)][U(O(t)Bu)(2)(CH(2)SiMe(3))(3)] (2) in high yield. Treatment of 2 with AgOTf fails to produce a U(V) derivative, but instead affords the U(IV) complex (Me(3)SiCH(2))Ag(μ-CH(2)SiMe(3))U(CH(2)SiMe(3))(O(t)Bu)(2)(DME) (3) in 64% yield. Complex 3 has been characterized by X-ray crystallography and is marked by a uranium-silver bond. In contrast, oxidation of 2 can be achieved via reaction with 0.5 equiv of Me(3)NO, producing the heteroleptic U(V) complex [Li(DME)(3)][U(O(t)Bu)(2)(CH(2)SiMe(3))(4)] (4) in moderate yield. We have also attempted the one-electron oxidation of complex 1. Thus, oxidation of 1 with U(O(t)Bu)(6) results in formation of a rare U(VI) alkyl complex, U(CH(2)SiMe(3))(6) (6), which is only stable below -25 °C. Additionally, the electronic properties of 1-4 have been assessed by SQUID magnetometry, while a DFT analysis of complexes 1 and 6 is also provided. 相似文献
85.
Cubo L Hambley TW Sanz Miguel PJ Carnero A Navarro-Ranninger C Quiroga AG 《Dalton transactions (Cambridge, England : 2003)》2011,40(2):344-347
The physical and biological properties have been determined for three Pt(IV) complexes with trans amine ligands: trans,trans,trans-[PtCl(2)(OH)(2)(dimethylamine)(isopropylamine)] (1(IV)), trans,trans,trans-[PtCl(2)(OH)(2)(dimethylamine)(methylamine)] (2(IV)) and trans,trans,trans-[PtCl(2)(OH)(2)(isopropylamine)(methylamine)] (3(IV)). The crystal structures of 2(IV) and 3(IV) reveal substantial strain resulting from repulsion between the amine ligands and the chlorido and hydroxido ligands. All three complexes have reduction potentials in the range -666 to -770 mV, values usually associated with high resistance to reduction and low cytotoxicity. However, the complexes all demonstrate surprisingly high cytotoxicity with values and trends that closely follow those seen for the Pt(II) congeners of these complexes. These results are consistent with more rapid reduction of the Pt(IV) complexes than would be expected based on the reduction potentials, perhaps associated with the trans arrangement of the chlorido ligands. 相似文献
86.
Masahisa Wada Yoshiharu Nishiyama Giovanni Bellesia Trevor Forsyth S. Gnanakaran Paul Langan 《Cellulose (London, England)》2011,18(2):191-206
The hydrogen bond arrangement in a complex of cellulose with ammonia has been studied using neutron crystallography in combination
with molecular dynamics simulations. The O6 atom of the hydroxymethyl group is donor in a highly occupied hydrogen bond to
an ammonia molecule. This rotating ammonia molecule is donor in partially occupied and transient hydrogen bonds to the O2,
O3 and O6 atoms of the hydroxyl groups of other chains. The hydrogen atom bound to the O3 atom is disordered but it is almost
always involved in some type of hydrogen bonding. It is donated in a hydrogen bond most of the time to the O5 atom on the
same chain. However, it also rotates away from this O5 atom to be donated to an ammonia molecule part of the time. On the
other hand the hydrogen atom bound to the O2 atom is free from hydrogen bonding most of the time. It is donated in a hydrogen
bond to the O6 atom on a neighboring chain only with a relatively small probability. These results provide new insights into
how hydrogen bonds are rearranged during the conversion of cellulose I to cellulose IIII by ammonia treatment. 相似文献
87.
Zinc sorption to hydrous manganese oxide (HMO)-coated clay was investigated macroscopically, kinetically, and spectroscopically. Adsorption edges and isotherms revealed that the affinity and capacity of the HMO-coated montmorillonite was greater than that of montmorillonite, and when normalized to the oxide present, the coatings behaved similarly to the discrete Mn oxide. Over two pH conditions, 5 and 6, a linear relationship was observed for the isotherms; further analysis with X-ray absorption spectroscopy (XAS) resulted in one type of sorption configuration as a function of loading and ionic strength at pH 5. However, at a surface loading of 10(-3) mol(Zn) g(HMO-coatedclay)(-1) when the pH increased from 5 to 7, the first shell distance decreased slightly, while the atoms and coordination numbers remained the same; this change may be attributed to an increase in electrostatic interactions. After a contact time of 4 months where an additional 60% of the sites become occupied, the slower sorption process was modeled as intraparticle surface diffusion. Best fit diffusivities ranged from 10(-18) to 10(-17) cm2/s, where a slower process was observed for the coated surface as compared to the discrete oxide. Interestingly, the porosity of the Mn oxide coating appears to be influenced by the substrate during its growth, as its increase and shift to a smaller pore size distribution resulted in a diffusivity between that observed for discrete HMO and montmorillonite. 相似文献
88.
Surface complexation of Pb(II) on amorphous iron oxide and manganese oxide: spectroscopic and time studies 总被引:1,自引:0,他引:1
Hydrous Fe and Mn oxides (HFO and HMO) are important sinks for heavy metals and Pb(II) is one of the more prevalent metal contaminants in the environment. In this work, Pb(II) sorption to HFO (Fe(2)O(3) x nH(2)O, n=1-3) and HMO (MnO(2)) surfaces has been studied with EXAFS: mononuclear bidentate surface complexes were observed on FeO(6) (MnO(6)) octahedra with PbO distance of 2.25-2.35 Angstrom and PbFe(Mn) distances of 3.29-3.36 (3.65-3.76) Angstrom. These surface complexes were invariant of pH 5 and 6, ionic strength 2.8 x 10(-3) to 1.5 x 10(-2), loading 2.03 x 10(-4) to 9.1 x 10(-3) mol Pb/g, and reaction time up to 21 months. EXAFS data at the Fe K-edge revealed that freshly precipitated HFO exhibits short-range order; the sorbed Pb(II) ions do not substitute for Fe but may inhibit crystallization of HFO. Pb(II) sorbed to HFO through a rapid initial uptake ( approximately 77%) followed by a slow intraparticle diffusion step ( approximately 23%) resulting in a surface diffusivity of 2.5 x 10(-15) cm(2)/s. Results from this study suggest that mechanistic investigations provide a solid basis for successful adsorption modeling and that inclusion of intraparticle surface diffusion may lead to improved geochemical transport depiction. 相似文献
89.
Zheng Deng Chang‐Jong Kang Mark Croft Wenmin Li Xi Shen Jianfa Zhao Richeng Yu Changqing Jin Gabriel Kotliar Sizhan Liu Trevor A. Tyson Ryan Tappero Martha Greenblatt 《Angewandte Chemie (International ed. in English)》2020,59(21):8240-8246
Given the consensus that pressure improves cation ordering in most of known materials, a discovery of pressure‐induced disordering could require recognition of an order–disorder transition in solid‐state physics/chemistry and geophysics. Double perovskites Y2CoIrO6 and Y2CoRuO6 polymorphs synthesized at 0, 6, and 15 GPa show B‐site ordering, partial ordering, and disordering, respectively, accompanied by lattice compression and crystal structure alteration from monoclinic to orthorhombic symmetry. Correspondingly, the long‐range ferrimagnetic ordering in the B‐site ordered samples are gradually overwhelmed by B‐site disorder. Theoretical calculations suggest that unusual unit‐cell compressions under external pressures unexpectedly stabilize the disordered phases of Y2CoIrO6 and Y2CoRuO6. 相似文献