Keggin型多阴离子[XW_(12)O_(40)]~(n-)(X=Si,Ge,P,As)电子性质的密度泛函理论研究

采用密度泛函理论方法研究了Keggin型多阴离子[XW12O40]n-(X=Si,Ge,P,As)的电子性质,在几何优化基础上,分析杂原子对体系的几何结构,电子性质,氧化还原性质的影响。结果表明:杂原子对多阴离子的键长有影响,变化规律与杂原子半径递变一致;杂原子的电子性质影响多阴离子的氧化性,多阴离子的氧化能力随杂原子的电负性增大而提高;杂原子的核电荷数越大,该多阴离子的氧化性越强;多阴离子的酸强度与杂原子的电负性次序一致。     

FeS_n(n=1~6)团簇的结构与电子性质

利用密度泛函理论对FeSn(n=1~6)团簇的结构和稳定性进行了分析。综合FeSn团簇基态的平均结合能、二阶能量差分、垂直电离势、最高占据分子轨道与最低未占据分子轨道之间的能隙(HOMO-LUMO-Gap)分析可知,n=4时FeSn的稳定性最显著。     

Co(Ⅱ)掺杂锐钛矿二氧化钛的理论研究

采用基于密度泛函理论(DFT)框架下的第一性原理平面波赝势(PWPP)方法,模拟计算Co(Ⅱ)掺杂锐钛矿TiO2,讨论了Co(Ⅱ)掺杂对锐钛矿的晶体结构、能隙、态密度等的影响。结果表明Co(Ⅱ)掺杂锐钛矿TiO2晶体后,Co(Ⅱ)的3d轨道进入禁带并与氧的2p轨道作用,使禁带宽度(Eg)变小,TiO2的吸收带红移,从而有助于TiO2的光催化活性。     

钙钛矿型复合氧化物LaCrO_(3-δ)的结构稳定性

为了研究氧空穴对LaCrO_(3-δ)结构稳定性的影响,首先对La Cr O3结构中氧空穴的形成过程进行了分析,然后建立了不同氧空穴浓度下的LaCrO_(3-δ)(δ为0.125~0.875)结构,并采用基于密度泛函理论的第一性原理对氧空穴形成能和LaCrO_(3-δ)结构稳定性进行了研究。结果表明,LaCrO_(3-δ)的氧空穴形成能随着δ的升高不断增大,而结构稳定性也随之不断降低。此外,根据氧空穴形成能的相对大小,发现在最稳定的LaCrO_(3-δ)(δ为0.125~0.500)结构中,氧空穴都排布在CrO_2层。因此,LaCrO_(3-δ)结构的稳定性不仅与氧空穴浓度有关,而且与氧空穴的排布方式有关。     

N^＋5、N^-5、N8、N10结构与稳定性的密度泛函理论

为了从分子水平探索典型氮原子簇化合物N^＋5,N^-5、N8、N10的结构特征和稳定性，采用B3LYP方法，在6—31G（d，p）基组水平下对N^＋5、N^-5、N8、N10的结构进行了优化，得到稳定的几何构型和分子轨道。通过稳定性分析发现，N^＋5属V型结构，N^-5属五元环结构，N8属亚稳态立方晶系结构；N^-5的化学稳定性优于N^＋5，N10的化学稳定性优于N8。     

Cu、N共掺杂锐钛矿型二氧化钛的理论研究

采用基于密度泛函理论(DFT)框架下的第一性原理平面波赝势(PWPP)方法,模拟计算了Cu、N共掺杂锐钛矿TiO2,讨论了Cu掺杂、N掺杂、Cu、N共掺杂对锐钛矿TiO2的晶体结构、能隙、态密度等的影响.结果表明Cu、N共掺杂锐钛矿TiO2晶体后,导带主要由N-2p和Ti-3d轨道上的电子构成,价带主要由O-2p和Cu...     

N+5、N-5、N8、N10结构与稳定性的密度泛函理论

为了从分子水平探索典型氮原子簇化合物N 5、N-5、N8、N10的结构特征和稳定性,采用B3LYP方法,在6-31G(d,p)基组水平下对N 5、N-5、N8、N10的结构进行了优化,得到稳定的几何构型和分子轨道.通过稳定性分析发现,N 5属V型结构,N-5属五元环结构,N8属亚稳态立方晶系结构;N-5的化学稳定性优于N 5,N10的化学稳定性优于N8.     

Zn3V2O8的电子结构与光学性质的理论研究

采用平面波超软赝势密度泛函理论的方法研究了Zn3V2O8的能带结构、电子态密度和光学特性.能带结果显示Zn3V2O8呈间接带隙的绝缘体型能带,其禁带宽度为2.9 eV.详细的电子态密度结果显示其费米面上的态密度达到20 e/eV,费米能级附近的能级由Zn3p、V3p和O2p电子形成,Zn3d和O2s之间有强的杂化作用.介电性能结果显示在4.4 ～5.7 eV附近有强的吸收峰,在20.6 eV附近有一个次强吸收峰;吸收光谱显示在6.8 eV处有强吸收,在20.7 eV处有一个较弱的吸收峰.     

Studies of palladium electrodeposition from baths based on Pd(NH3)2X2 Part II: X=Br and X=NO2

The chemistry and electrochemistry of electroplating baths based on Pd(NH₃)₂Br₂ and Pd(NH₃)₂(NO₂)₂ has been investigated and compared with that previously reported for Pd(NH₃)₂Cl₂. It is shown that electroactive species in all the baths is Pd(NH₃) ₄ ²⁺ and, hence, the mechanisms and current efficiencies for the cathodic deposition of palladium metal are similar in all three media. On the other hand, only in bromide electrolytes is the palladium found to dissolve anodically.     

Carbon doped with binary heteroatoms (N,X–C,where X = P,B, or S) derived from polypyrrole for enhanced electromagnetic wave absorption at microwave frequencies

Dual heteroatom-doped carbon materials show great promise as electromagnetic wave absorbers. However, synthesizing carbons containing multiple heteroatoms at controlled heteroatom doping levels has provided challenges to date. Herein, we report a simple method for manufacturing dual heteroatom doped carbons (N,X–C, where X = P, B, or S) by direct carbonization of polypyrrole synthesized in the presence of H₃PO₄, H₃BO₃, or H₂SO₄, respectively. The heteroatom content of the N,X–C products could be precisely tuned by varying amounts of acid dopant used in the polypyrrole synthesis. The N,X–C materials showed excellent electromagnetic wave absorption properties, especially N,S₁–C (prepared using equimolar amounts of pyrrole and H₂SO₄) which offered a wide absorption bandwidth up to 6.6 GHz (11.38–18 GHz), and a RL_min of ?32.3 dB (14.2 GHz) at 2.5 mm at a ?ller loading of 9.0 wt%. The outstanding electromagnetic wave absorption performance of N,S₁–C was attributed to the presence of N dopant species, defects, C–S, and C–SO_x groups, which optimized dipole polarization and conduction loss in the dielectric loss leading to excellent impedance matching.     

稀土配合物[Ln(C3H7NO2)-x-(C3H4N2)(H2O)](ClO4)3(Ln=La,-x-=3;Ln=Pr,Nd,Sm,-x-=2)的合成、表征与热分析

合成了稀土高氯酸盐与咪唑、DL α 丙氨酸的4种配合物晶体。经傅里叶变换红外光谱(FTIR)、元素分析和化学分析测定后确定其组成为[Ln(C3H7NO2)x(C3H4N2)(H2O)](ClO4)3(Ln=La,x=3;Ln=Pr,Nd,Sm,x=2)。用差示扫描量热法(DSC)测定了4种配合物的热分解数据,4个配合物开始熔化分解的温度分别为502 5K,532 4K,495 7K,516 7K,配合物有较高的热稳定性。     

The metal-chain complexes (X)[Os(CO)3(CNBut)]3Mn(CO)5 (X=Cl,Br, I)

In what is a new metal-chain forming reaction, (X)[Os(CO)₃(CNBu^t)]₃Mn(CO)₅ (X=Cl, Br, I) complexes have been prepared by the successive addition of Os(CO)₄(CNBu^t) to Mn(CO)₅(X) in hexane. The crystal structure of the iodo derivative reveals it to contain an approximately linear Os₃ Mn chain of metal atoms.     

General Construction of Amine via Reduction of N=X (X = C,O, H) Bonds Mediated by Supported Nickel Boride Nanoclusters

Amines play an important role in synthesizing drugs, pesticides, dyes, etc. Herein, we report on an efficient catalyst for the general construction of amine mediated by nickel boride nanoclusters supported by a TS-1 molecular sieve. Efficient production of amines was achieved via catalytic hydrogenation of N=X (X = C, O, H) bonds. In addition, the catalyst maintains excellent performance upon recycling. Compared with the previous reports, the high activity, simple preparation and reusability of the Ni-B catalyst in this work make it promising for industrial application in the production of amines.     

煤及油母中常见C-X(X=N,S)的解离能

煤及油页岩中除了碳、氢和氧原子是主要的组成元素外,氮和硫等杂原子大都以C-X（X=N,S）的键合形式存在,在其结构及转化利用中同样发挥重要的作用。认识C-X的解离能,有助于建立氮、硫热解过程中的迁移模型,丰富对煤及油母中常见化学键性质的认识,对发展高效清洁的能源利用技术至关重要。利用双杂化密度泛函方法,系统研究了煤及油母中典型C-X键的解离能（BDE）范围。研究结果表明,煤及油母中常见C-N和C-S键的BDE值范围分别是154.1~55.7 kcal·mol^-1和83.0~56.6 kcal·mol^-1。在热解过程中,苯硫类自由基以及苯胺类自由基会在初期产生,其次才是巯基、胺类自由基等侧链取代自由基脱落。C-S键的整体BDE值范围比其他类型化学键更低,各类化学键最低BDE值的高低顺序符合O-H > C-H > C-C > C-N > C-S > C-O的规律,其中,只有当有PhOx生成时,C-S > C-O,否则C-O > C-S。     

Stereodynamics Study of the Reaction of O(3P) with CH4 (v = 0, j = 0)

A new London-Eyring-Polanyi-Sato (LEPS) potential energy surface (PES) is used in the O + CH₄ → OH + CH₃ reaction via the quasiclassical trajectory method (QCT). Comparing with the experiments and the former ab initio calculations, the new LEPS PES describes the actual potential energy surface of the O + CH₄ reaction successfully. The four polarization dependent “generalized” differential cross sections (PDDCS) are presented in the center of mass frame. In the meantime, the distribution of dihedral angle [P(φ_r), the distribution of angle between k and j′ (P(θ_r)] and the angular distribution of product rotational vectors in the form of polar plots in θ_r and φ_r (P(θ_r, φ_r) are calculated. The isotope effect for the reactions O + CD₄ is also calculated. These results are in good agreement with the experiments.     

Thermal expansion coefficient and relaxation parameters of glasses in the system GaX2-GeX2-Sb2X3 (X = S, Se)

The concentration behavior of the thermal expansion coefficient of glasses in the system GaX₂-GeX₂-Sb₂X₃ (X = S, Se) has been studied in two sections. Parameters characterizing the relaxation properties of the glasses have been calculated on the basis of the Tool-Narayanaswamy theory from experimental temperature dependences of the thermal expansion coefficient in the softening range. Temperature dependences of the viscosity have been calculated under the assumption of equal free activation energies for the relaxation and viscous flow.     

A general synthesis of titanocene(III) complexes Cp2TiX(PMe3) (X=F,Cl, Br,I, Me,SMe) by comproportionation of Cp2TiX2 and Cp2Ti(PMe3)

The titanocene(III) complexes Cp₂TiX(PMe₃) (X=F, Cl, Br, I, Me, SMe) are readily synthesized by comproportionation reactions of Cp₂Ti(PMe₃)₂ and Cp₂TiX₂. The products are characterized by EPR spectroscopy.