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191.
Petra Vasko Shuai Wang Heikki M. Tuononen Prof. Philip P. Power 《Angewandte Chemie (International ed. in English)》2015,54(12):3802-3805
Reaction of the tin cluster Sn8(Ar)4 (Ar=C6H2‐2,6‐(C6H3‐2,4,6‐Me3)2) with excess ethylene or dihydrogen at 25 °C/1 atmosphere yielded two new clusters that incorporated ethylene or hydrogen. The reaction with ethylene yielded Sn4(Ar)4(C2H2)5 that contained five ethylene moieties bridging four aryl substituted tin atoms and one tin–tin bond. Reaction with H2 produced a cyclic tin species of formula (Sn(H)Ar)4, which could also be synthesized by the reaction of {(Ar)Sn(μ‐Cl)}2 with DIBAL‐H. These reactions represent the first instances of direct reactions of isolable main‐group clusters with ethylene or hydrogen under mild conditions. The products were characterized in the solid state by X‐ray diffraction and IR spectroscopy and in solution by multinuclear NMR and UV/Vis spectroscopies. Density functional theory calculations were performed to explain the reactivity of the cluster. 相似文献
192.
Access to Stable Metalloradical Cations with Unsupported and Isomeric Metal–Metal Hemi‐Bonds
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Xin Zheng Dr. Xingyong Wang Dr. Zaichao Zhang Yunxia Sui Prof. Xinping Wang Prof. Philip P. Power 《Angewandte Chemie (International ed. in English)》2015,54(31):9084-9087
Metalloradical species [Co2Fv(CO)4].+ ( 1 .+, Fv=fulvalenediyl) and [Co2Cp2(CO)4].+ ( 2 .+, Cp=η5‐C5H5), formed by one‐electron oxidations of piano‐stool cobalt carbonyl complexes, can be stabilized with weakly coordinating polyfluoroaluminate anions in the solid state. They feature a supported and an unsupported (i.e. unbridged) cobalt–cobalt three‐electron σ bond, respectively, each with a formal bond order of 0.5 (hemi‐bond). When Cp is replaced by bulkier Cp* (Cp*=η5‐C5Me5), an interchange between an unsupported radical [Co2Cp*2(CO)4].+ (anti‐ 3 .+) and a supported radical [Co2Cp*2(μ‐CO)2(CO)2].+ (trans‐ 3 .+) is observed in solution, which cocrystallize and exist in the crystal phase. 2 .+ and anti‐ 3 .+ are the first stable thus isolable examples that feature an unsupported metal–metal hemi‐bond, and the coexistence of anti‐ 3 .+ and trans‐ 3 .+ in one crystal is unprecedented in the field of dinuclear metalloradical chemistry. The work suggests that more stable metalloradicals of metal–metal hemi‐bonds may be accessible by using metal carbonyls together with large and weakly coordinating polyfluoroaluminate anions. 相似文献
193.
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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195.
Xiaohui Guo a Jianzhong Lin a b Deming Nie a a Institute of Fluid Mechanics China Jiliang University Hangzhou China b State Key Laboratory of Fluid Power Transmission Control Zhejiang University Hangzhou China 《中国颗粒学报》2011,9(2)
The drag force on a cylindrical particle is calculated using lattice Boltzmann method.The results show that the drag coefficient of a particle with different orientation angles decreases with increasing Reynolds number.When the principal axis of the particle is parallel to flow,the drag coefficient is much larger than that of others and decreases fastest with increasing Reynolds number,which becomes more obvious with increasing particle aspect ratio.When the principal axis of the particle is inclined to flo... 相似文献
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R Power JP Reid S Anand D McGloin A Almohamedi NS Mistry AJ Hudson 《The journal of physical chemistry. A》2012,116(35):8873-8884
The binary coalescence of aqueous droplets has been observed in a single-beam gradient-force optical trap. By measuring the time-dependent intensity for elastic scattering of light from the trapping laser, the dynamics of binary coalescence have been examined and the time scale for equilibration of a composite droplet to ambient conditions has been determined. These data are required for modeling the agglomeration of aqueous droplets in dense sprays and atmospheric aerosol. Elastic-light scattering from optically trapped particles has not been used previously to study the time-resolved dynamics of mixing. It is shown to offer a unique opportunity to characterize the binary coalescence of aqueous droplets with radii from 1 to 6 μm. The study of this size regime, which cannot be achieved by conventional imaging methods, is critical for understanding the interactions of droplets in the environment of dense sprays. 相似文献
199.
Brown ZD Vasko P Fettinger JC Tuononen HM Power PP 《Journal of the American Chemical Society》2012,134(9):4045-4048
Reaction of the diarylgermylene Ge(Ar(Me(6)))(2) [Ar(Me(6)) = C(6)H(3)-2,6-(C(6)H(2)-2,4,6-(CH(3))(3))(2)] with tert-butyl isocyanide gave the Lewis adduct species (Ar(Me(6)))(2)GeCNBu(t), in which the isocyanide ligand displays a decreased C-N stretching frequency consistent with an n → π* back-bonding interaction. Density functional theory confirmed that the HOMO is a Ge-C bonding combination between the lone pair of electrons on the germanium atom and the C-N π* orbital of the isocyanide ligand. The complex undergoes facile C-H bond activation to produce a new diarylgermanium hydride/cyanide species and isobutene via heterolytic cleavage of the N-Bu(t) bond. 相似文献
200.
复合低温相变蓄冷材料的实验研究 总被引:3,自引:0,他引:3
提出自行研制的一种复合低温相变蓄冷材料,通过实验分析了该蓄冷材料的融点、相变潜热和凝固融化过程曲线.该材料由有机物和无机物混合而成,用示差扫描量热仪(DSC)来测定该蓄冷材料的融点、相变潜热;用低温冰箱测试凝固融化过程材料的均匀稳定性.实验结果表明,该材料具有良好的性能,适用于医药、食品、冰箱及冷库等蓄冷装置中. 相似文献