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Fu‐Sheng Guo Yan‐Cong Chen Ming‐Liang Tong Akseli Mansikkamki Richard A. Layfield 《Angewandte Chemie (International ed. in English)》2019,58(30):10163-10167
Abstraction of iodide from [(η5‐C5iPr5)2UI] ( 1 ) produced the cationic uranium(III) metallocene [(η5‐C5iPr5)2U]+ ( 2 ) as a salt of [B(C6F5)4]?. The structure of 2 consists of unsymmetrically bonded cyclopentadienyl ligands and a bending angle of 167.82° at uranium. Analysis of the bonding in 2 showed that the uranium 5f orbitals are strongly split and mixed with the ligand orbitals, thus leading to non‐negligible covalent contributions to the bonding. Investigation of the dynamic magnetic properties of 2 revealed that the 5f covalency leads to partially quenched anisotropy and fast magnetic relaxation in zero applied magnetic field. Application of a magnetic field leads to dominant relaxation by a Raman process. 相似文献
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The use of sodium hexametaphosphate in the spectrofluorometric determination of trace amounts of cerium(III) ions is described. Sodium hexametaphosphate acts as a specific reagent for enhancing the fluorescence intensity of cerium(III) in aqueous solutions. The apparent excitation and fluorescence wavelength used are 304 and 344 nm, respectively. Maximum fluorescence intensity is obtained by irradiating Ce(III) dissolved in 5.346 g/l sodium hexametaphosphate solution at room temperature. The fluorescence varies linearly with the concentration of cerium(III) in the range of 0.001-60 microg/ml. The coefficient of variation for 45 microg/ml Ce(III) in 5.346 g/l sodium hexametaphosphate solution is 1. The quenching effects of other lanthanides and some inorganic anions are given. This technique permits a direct and rapid determination of cerium(III) in rare earth mixtures and cerium concentrates. 相似文献
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Chris Gendy Akseli Mansikkamki Juuso Valjus Joshua Heidebrecht Paul Chuk‐Yan Hui Guy M. Bernard Heikki M. Tuononen Roderick E. Wasylishen Vladimir K. Michaelis Roland Roesler 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(1):160-164
Flexible, chelating bis(NHC) ligand 2 , able to accommodate both cis‐ and trans‐coordination modes, was used to synthesize ( 2 )Ni(η2‐cod), 3 . In reaction with GeCl2, it produced ( 2 )NiGeCl2, 4 , featuring a T‐shaped Ni0 and a pyramidal Ge center. Complex 4 could also be prepared from [( 2 )GeCl]Cl, 5 , and Ni(cod)2, in a reaction that formally involved Ni–Ge transmetalation, followed by coordination of the extruded GeCl2 moiety to Ni. A computational analysis showed that 4 possesses considerable multiconfigurational character and the Ni→Ge bond is formed through σ‐donation from the Ni 4s, 4p, and 3d orbitals to Ge. (NHC)2Ni(cod) complexes 9 and 10 , as well as (NHC)2GeCl2 derivative 11 , incorporating ligands that cannot accommodate a wide bite angle, failed to produce isolable Ni–Ge complexes. The isolation of ( 2 )Ni(η2‐Py), 12 , provides further evidence for the reluctance of the ( 2 )Ni0 fragment to act as a σ‐Lewis acid. 相似文献
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Vincenzo Piccialli Sabrina Zaccaria Giorgia Oliviero Akseli Hemminki Valentina Romano Roberto Centore 《Tetrahedron》2010,66(48):9370-9378
Four novel C30 polyether bis-spiroketals, displaying selective inhibition of the BT474 breast-derived cancer cell line, have been obtained from squalene through an unprecedented one-step, RuO4-catalysed, cascade process characterised by a tandem oxidative pentacyclization/double oxidative spiroketalization sequence. Preliminary studies indicate that the Ru-mediated spiroketalization steps proceed with retention of configuration at the forming spirocentres. A similarity with the oxidative behaviour of PCC has been disclosed. 相似文献
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Sodium triphosphate acts as a specific reagent for enhancing the fluorescence intensity of cerium(III). The purpose of this study was to investigate the spectrofluorimetric determination of trace amounts of Ce(III) in sodium triphosphate solution. The excitation and emission wavelengths are 303.5 nm and 353 nm respectively. Optimum sodium triphosphate concentration is found to be 0.074 g l(-1) at room temperature. The fluorescence varies linearly with the concentration of cerium(III) in the range 0.001-45 mug ml(-1). The detection limit is 9.4 x 10(-4)mug ml(-1). The relative standard deviations for 30 mug ml(-1) and 0.05 mug ml(-1) Ce(III) in 0.074 g l(-1) sodium triphosphate solution are 1.1% and 0.72% respectively. Quenching effects of other lanthanides and some inorganic anions are described. This method is a direct and rapid analytical method for the determination of Ce(III) in rare earth mixtures and cerium concentrates. 相似文献
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Coordination Complexes of a Neutral 1,2,4‐Benzotriazinyl Radical Ligand: Synthesis,Molecular and Electronic Structures,and Magnetic Properties 下载免费PDF全文
Dr. Ian S. Morgan Akseli Mansikkamäki Georgia A. Zissimou Dr. Panayiotis A. Koutentis Mathieu Rouzières Dr. Rodolphe Clérac Dr. Heikki M. Tuononen 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(44):15843-15853
A series of d‐block metal complexes of the recently reported coordinating neutral radical ligand 1‐phenyl‐3‐(pyrid‐2‐yl)‐1,4‐dihydro‐1,2,4‐benzotriazin‐4‐yl ( 1 ) was synthesized. The investigated systems contain the benzotriazinyl radical 1 coordinated to a divalent metal cation, MnII, FeII, CoII, or NiII, with 1,1,1,5,5,5‐hexafluoroacetylacetonato (hfac) as the auxiliary ligand of choice. The synthesized complexes were fully characterized by single‐crystal X‐ray diffraction, magnetic susceptibility measurements, and electronic structure calculations. The complexes [Mn( 1 )(hfac)2] and [Fe( 1 )(hfac)2] displayed antiferromagnetic coupling between the unpaired electrons of the ligand and the metal cation, whereas the interaction was found to be ferromagnetic in the analogous NiII complex [Ni( 1 )(hfac)2]. The magnetic properties of the complex [Co( 1 )(hfac)2] were difficult to interpret owing to significant spin–orbit coupling inherent to octahedral high‐spin CoII metal ion. As a whole, the reported data clearly demonstrated the favorable coordinating properties of the radical 1 , which, together with its stability and structural tunability, make it an excellent new building block for establishing more complex metal–radical architectures with interesting magnetic properties. 相似文献
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Michelle Faust Aimee M. Bryan Akseli Mansikkamäki Petra Vasko Prof. Marilyn M. Olmstead Prof. Heikki M. Tuononen Prof. Fernande Grandjean Prof. Gary J. Long Prof. Philip P. Power 《Angewandte Chemie (International ed. in English)》2015,54(44):12914-12917
The characterization of the unstable NiII bis(silylamide) Ni{N(SiMe3)2}2 ( 1 ), its THF complex Ni{N(SiMe3)2}2(THF) ( 2 ), and the stable bis(pyridine) derivative trans‐Ni{N(SiMe3)2}2(py)2 ( 3 ), is described. Both 1 and 2 decompose at ca. 25 °C to a tetrameric NiI species, [Ni{N(SiMe3)2}]4 ( 4 ), also obtainable from LiN(SiMe3)2 and NiCl2(DME). Experimental and computational data indicate that the instability of 1 is likely due to ease of reduction of NiII to NiI and the stabilization of 4 through dispersion forces. 相似文献
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The distribution coefficients of rare earth elements and thorium with Dowex 2-X8, 200-400 mesh, a strongly basic anion-exchange resin, have been determined regarding four different concentrations of sodium trimetaphosphate (3 x 10(-3), 5 x 10(-3), 7 x 10(-3) and 0.01 M). The separation of the rare earths and thorium obtained from an Australian monazite has been investigated by anion-exchange chromatography with sodium trimetaphosphate concentration gradient on a Dowex 2-X8 ion-exchange columns. The order of elution of the elements was the reverse of the order of elution of the same elements on Dowex 1 resin. The elution was investigated using 5 mg and 250 mg samples. In the separation of 5 mg samples, all elements were separated in 29 min. It has been seen that the elution peaks are narrow, tailing effects are very small, Dy and Y are well separated. Qualitative and quantitative determinations were realized by spectrofluorometry. 相似文献