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81.
82.
The relative stabilities of thiourea in water are investigated computationally by considering thiourea–water complexes containing up to 1–6 water molecules (CS(NH2)2(H2O)n=1–6) using density functional theory and MP2 ab initio molecular orbital theory. The results show that the thiourea complex is stable and has an unusually high affinity for incoming water molecules. The clusters are progressively stabilized by the addition of water molecules, as indicated by the increasing of the binding energy. The binding energy of the cluster to each H2O molecule is about 33 kJ mol−1 for n=1–5.The C–S bond, N–C bond distance, Mulliken populations and binding energy keep approximately constant as the clusters increase in size with an increasing number of H2O molecules. As the solvation progresses, the C–S distance increases monotonically while the Mulliken populations on the C–S bond reduces monotonically with the addition of each H2O molecule, indicating that the C–S bond of the thiourea unit in the clusters is de-stabilized with an increasing number of H2O molecules. Charge transfers for the clusters are mainly found at N, S atoms of the thiourea. 相似文献
83.
采用三元胺及二元胺混配方法进行[Co(N)5Cl]2+配合物的合成,分离出分别由三元胺配体和二胺配体构成的2个钴胺配合物。晶体结构测定表明由三元胺配体构成的钴胺配合物中,三元胺为N-(2-Aminoethyl)-1,3-propanediamine(记为2,3-tri),但并未以六胺形式配位[Co(N)6]3+,而以六胺五配位形式形成[Co(N)6Cl]2+,这 相似文献
84.
采用ab initio RHF,MP2和B3LYP方法以及LanL2DZ和SDD基组计算了四面体锌族卤素阴离子化合物(MX42-,M=Zn(Ⅱ),Cd(Ⅱ),Hg(Ⅱ);X=F-,Cl-,Br-,I-)和钛族卤化物(MX4,M=Ti(Ⅳ),Zr(Ⅳ),Hf(Ⅳ);X=F-,Cl-,Br-,I-)的几何构型和振动频率。计算结果表明,LanL2DZ基组是合适的基组,能得到合理的电荷分布,几何参数以及振动频率。在锌族卤化物的计算中发现,角弯曲振动频率与实测值相当一致,键伸缩振动频率略为偏低,这主要是由于计算的键长略为偏长所致。MP2方法计算的振动频率更接近于实测值。在钛族卤化物的计算中,三种计算方法都相当地再现了实测值,而以B3LYP方法更为满意。 相似文献
85.
用密度泛函理论研究了氢原子的污染对于Ru(0001)表面结构的影响. 通过PAW(projector-augmented wave)总能计算研究了p(1×1)、p(1×2)、(3^(1/2)×3^(1/2))R30°和p(2×2)等几种氢原子覆盖度下的吸附结构, 以及在上述结构下Ru(0001)面fcc(面心立方)格点和hcp(六方密堆)格点的氢原子吸附. 所得结果表明, 在p(1×1)-H、p(1×2)-H、(3^(1/2)×3^(1/2))R30°-H和p(2×2)-H几种H原子覆盖度下, 以p(1×1)-H结构单个氢原子吸附能为最大. 在p(1×1)-H吸附结构下,由于氢原子吸附导致的Ru(0001) 表面第一层Ru 原子收缩的理论计算数值分别为-1.11%(hcp 吸附)和-1.55%(fcc 吸附), 因此实际上最有可能的情况是两种吸附方式都有一定的几率. 而实验中观察到的“清洁”Ru(0001)表面实际上是有少量氢原子污染的表面. 不同覆盖度和氢分压下氢原子吸附的污染对Ru(0001)表面结构有极大的影响,其表面的各种特性都会随覆盖度的不同而产生相应的变化. 相似文献
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88.
为满足便携式投影仪的市场需求,设计了一种基于LED微型阵列的投影系统。该系统由显示单元和投影物镜构成。采用尺寸为12 mm×9 mm的自发光LED微型阵列作为系统的显示单元,利用光学设计软件设计了投影物镜。投影物镜采用反远距光学结构,全视场角为80°,焦距为8 mm,属于强光、广角镜头。在空间频率20 lp/mm处,该物镜的调制传递函数大于0. 85,畸变小于2%,符合投影系统的设计要求。该投影系统具有体积小,结构简单,投影效果好,易加工等诸多优势,可为第三代投影技术的发展提供参考。 相似文献
89.
Construction of Hybrid Bimetallic Uranyl Compounds Based on a Preassembled Terpyridine Metalloligand
Xianghe Kong Dr. Kongqiu Hu Dr. Lei Mei Dr. Qunyan Wu Zhiwei Huang Kang Liu Prof. Zhifang Chai Prof. Changming Nie Prof. Weiqun Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(6):2124-2130
Six hybrid uranyl–transition metal compounds [UO2Ni(cptpy)2(HCOO)2(DMF)(H2O)] ( 1 ), [UO2Ni(cptpy)2(BTPA)2] ( 2 ), [UO2Fe(cptpy)2(HCOO)2(DMF)(H2O)] ( 3 ), [UO2Fe(cptpy)2(BTPA)2] ( 4 ), [UO2Co(cptpy)2(HCOO)2(DMF)(H2O)] ( 5 ), and [UO2Co(cptpy)2(BTPA)2] ( 6 ), based on bifunctional ligand 4′-(4-carboxyphenyl)-2,2′:6′,2′′-terpyridine (Hcptpy) are reported (H2BTPA = 4,4′-biphenyldicarboxylic acid). Single-crystal XRD revealed that all six compounds feature similar metalloligands, which consist of two cptpy− anions and one transition metal cation. The metalloligand M(cptpy)2 can be considered to be an extended linear dicarboxylic ligand with length of 22.12 Å. Compounds 1 , 3 , and 5 are isomers, and all of them feature 1D chain structures. The adjacent 1D chains are connected together by hydrogen bonds and π–π interactions to form a 3D porous structure, which is filled with solvent molecules and can be exchanged with I2. Compounds 2 , 4 , and 6 are also isomers, and all of them feature 2D honeycomb (6,3) networks with hexagonal units of dimensions 41.91×26.89 Å, which are the largest among uranyl compounds with honeycomb networks. The large aperture allows two sets of equivalent networks to be entangled together to result in a 2D+2D→3D polycatenated framework. Remarkably, these uranyl compounds exhibit high catalytic activity for cycloaddition of carbon dioxide. Moreover, the geometric and electronic structures of compounds 1 and 2 are systematically discussed on the basis of DFT calculations. 相似文献
90.
Shilin Jiang Dr. Jianhui Lan Dr. Lin Wang Dr. Yalan Liu Yuke Zhong Yichuan Liu Dr. Liyong L.-Y. Yuan Dr. Lirong Zheng Prof. Zhifang Chai Prof. Weiqun Shi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(45):11721-11729
Molten salt electrolysis is a vital technique to produce high-purity lanthanide metals and alloys. However, the coordination environments of lanthanides in molten salts, which heavily affect the related redox potential and electrochemical properties, have not been well elucidated. Here, the competitive coordination of chloride and fluoride anions towards lanthanide cations (La3+ and Nd3+) is explored in molten LiCl-KCl-LiF-LnCl3 salts using electrochemical, spectroscopic, and computational approaches. Electrochemical analyses show that significant negative shifts in the reduction potential of Ln3+ occur when F− concentration increases, indicating that the F− anions interact with Ln3+ via substituting the coordinated Cl− anions, and confirm [LnClxFy]3−x−y (ymax=3) complexes are prevailing in molten salts. Spectroscopic and computational results on solution structures further reveal the competition between Cl− and F− anions, which leads to the formation of four distinct Ln(III) species: [LnCl6]3−, [LnCl5F]3−, [LnCl4F2]3− and [LnCl4F3]4−. Among them, the seven-coordinated [LnCl4F3]4− complex possesses a low-symmetry structure evidenced by the pattern change of Raman spectra. After comparing the polarizing power (Z/r) among different metal cations, it was concluded that Ln−F interaction is weaker than that between transition metal and F− ions. 相似文献