A computational study of interplay between hydride bonding and cation–π interactions: H-Mg-H···X···Y triads (X = Li+, Na+, Y = C2H2, C2H4, C6H6) as model systems

In the present study, H-Mg-H···X···Y (X = Li⁺, Na⁺ and Y = C₂H₂, C₂H₄, C₆H₆) triads have been investigated at MP2/6-311++G(2d,2p) computational level to characterise cooperative effects between hydride bonding and cation–π interactions. Molecular geometries, binding energies, cooperative energies and many-body interaction energies were evaluated. The diminutive energy values in triads with Li⁺ are larger than respective values in triads with Na⁺. The electronic properties of the complexes are analysed using parameters derived from the quantum theory of atoms in molecules methodology.     

Al2O3X(X=H,D,T)的电子振动近似理论方法研究

用密度泛函理论(DFT)方法在6-311 G(d,p)水平上对Al2O3X(X=H,D,T)分子较低能量的几何构型进行了优化.计算结果表明该分子有两个可能基态,即Al2O3X(X=H,D,T)(2A′)Cs和Al2O3X(X=H,D,T)(2B2)C2v.全电子计算了氢同位素分子及Al2O3X(X=H,D,T)的能量E、定容热容CV和熵S.应用电子振动近似理论,即用单个分子Al2O3X(X=H,D,T)中的电子和振动能量和熵近似代表它们处于固态时的能量和熵,计算得到固体Al2O3的氢化热力学函数ΔH0,ΔS0,ΔG0以及平衡压力与温度的关系.当Al2O3吸附氢(氘,氚)形成C2v对称性气态Al2O3X(X=H,D,T)对应的固体时,氢气可以排代氘气,氘气可以排代氚气.这种排代效应非常不明显;形成Cs对称性气态Al2O3X(X=H,D,T)对应的固体时,反应的氢氘氚排代效应的顺序为氚排代氘,氘排代氢,与钛等的氢氘氚排代效应的顺序相反.总体而言,这种排代效应都非常弱.随着温度的增加,这一系列反应的氢氘氚排代效应趋于消失.     

SeX(X=H,C,N,O)的结构与势能函数

用密度泛函B3LYP方法对SeX(X=H,C,N,O) 分子体系进行了理论研究,得到SeX(X=H,C,N,O) 分子体系的基态电子状态的平衡几何Re和离解能De,并在计算出来的一系列单点势能基础上,用正规方程组拟合Murrell-Sorbie(M-S)势能函数,得到相应态的解析势能函数,光谱参数Be、αe、ωe、和ωeχe为:HSe:7.74786cm-1、0.22000cm-1、2425.33344cm-1 and 39.51563cm-1;SeC:0.56678cm-1、0.00370cm-1、1021.70315cm-1、5.10000cm-1;NSe:0.45528cm-1、0.00375cm-1、946.30895cm-1、4.98923cm-1;OSe:0.45296cm-1、0.00001cm-1、889.77025cm-1、4.55983cm-1.由此计算对应的光谱参数和力学性质.结果表明SeX(X=H,C,N,O) 分子体系是可稳定存在的.     

配合物Eu(C5H8NO3)2(C3H5N2)2Cl3·3H2O光致发光性能

利用OPO激光激发光谱和三维荧光光谱研究了配合物Eu(C5H8NO3)2(C3H5N2)2Cl3·3H2O固体粉末在不同激发光源下的荧光特性,测试了不同浓度配合物水溶液的荧光光谱.固体荧光结果显示该配合物具有很好的荧光性能,当激发光波长为320-400nm时,产生波长分别为400-500nm、580-620nm及690-710nm的三个荧光区;当激发光波长为700-880nm时产生峰值为450nm升频转换荧光,激发光波长为700-800nm时产生峰值分别为590nm和615nm的升频转换荧光.溶液荧光结果表明在10-4-10-2mol/L浓度范围内荧光强度与溶液浓度呈正相关.对其可能的发光机制进行了探讨.     

Eu(C8H7O3)3·C12H8N2·H2O配合物的合成与表征

合成了新的Eu(C8H7O3)3·C12H8N2·H2O配合物.并经元素分析、摩尔电导、IR、UV、1H NMR等表征,初步确定配体3-甲氧基苯甲酸以桥式双齿形式和Eu(Ⅲ)配位.     

Theoretical investigation on structures,stability and properties of [P,X, Y] (X=C,Si; Y = O,S) isomers

The structures, energetics and stability of the [P, X, Y] (X?=?C, Si; Y?=?O, S) radicals are explored by means of the density functional theory and ab initio levels. Seventeen [P, X, Y] isomers and 14 interconversion transition states are obtained at the B3LYP/6-311G(d) level. At the CCSD(T)/6-311?+?G(2df)//QCISD/6-311G(d)?+?ZPVE level, the lowest-lying isomers are the linear PCO 1a (0.0?kcal/mol), PCS 1b (0.0) and the three-membered ring cPSiO 1c (0.0), cPSiS 1d (0.0) on their respective potential energy surfaces. These four isomers exhibit considerably not only thermodynamic but also kinetic stabilities. Additionally, the cyclic cPCS 2b (32.8) and linear PSiS 2d (18.6) possess also high kinetic stability. All of six isomers 1a, 1b, 2b, 1c, 1d and 2d are considerably stabilized by a barrier of at least 20?kcal/mol, and may be detected in the laboratory or interstellar space. Their valence bond structures and possible formation strategies in the laboratory and space are discussed in detail. Finally, the similarities and discrepancies on structures and stabilities between [P, X, Y] (X?=?C, Si; Y?=?O, S) isomers are compared. These predicted results are highly expected to be informative for the future identification of [P, X, Y] (X?=?C, Si; Y?=?O, S) in the laboratory and space.     

糖精钴水合物[Co(C7H4NO3S)2(H2O)4]·2H2O的合成及晶体结构

以糖精钠(sac-Na)、丙氨酸和硝酸钴为原料合成得到糖精钴琥珀色块状晶体,采用红外、X射线单晶衍射对配合物进行了表征,该晶体属单斜晶系,空间群为P21/c,晶胞参数为:a=0.79269(5)nm,b=1.61407(10)nm,c=0.77026 (5) nm,α=90°,β=99.695(7)°,Ⅴ=0.97145 (11) nm3,Z=2,Dc=1.817g/cm3,F(000)=546,R=0.0278.结构分析表明,中心Co离子与4个O原子和两个N原子配位,处于四角双锥八面体配位环境中,4个水分子在赤道平面上与Co离子配位,晶胞中还包含有2个游离的结晶水,形成了含6个水分子的结晶物.     

Bi离子掺杂GeO2-Al2O3-M(M=Na2O,BaO,Y2O3)玻璃的光学性质

用高温熔融法制备了Bi离子掺杂浓度为1mol%的GeO-B2O3-Na2O (GBNB),GeO2-Al2O3-Na2O(GANB),GeO2-Al2O3-BaO(GABB)和GeO2-Al2O3-Y2O3(GAYB)玻璃.测定了样品玻璃的差热曲线、吸收、发射光谱及荧光衰减曲线.实验发现GBNB,GANB,GAYB,GABB的吸收边带逐步发生红移.由于这些吸收边带是由Bi3+的6s2电子到Bi5+ 6s0空轨道的跃迁引起.因此推断GBNB,GANB,GAYB,GABB玻璃中Bi5+离子的含量逐步增加.在GABB,GAYB,GANB三个样品中观察到发光中心约1220nm超宽带荧光发射.荧光强度从GABB,GAYB,GANB逐步减弱,荧光半高宽和荧光寿命逐步变小.这些超宽带的荧光归属为Bi5+离子的发光所致.从吸收与荧光光谱的变化,推断在GeO2-Al2O3玻璃中引入BaO,Y2O3组分有利于Bi5+离子的形成.讨论了BaO,Y2O3化学组分对Bi离子在玻璃中的价态影响的内在机理.     

Strengthening of the halogen-bonding by an aerogen bond interaction: substitution and cooperative effects in O3Z···NCX···NCY (Z = Ar,Kr, Xe; X = Cl,Br, I; Y = H,F, OH) complexes

The geometry, interaction energy and bonding properties of ternary complexes O₃Z···NCX···NCY (Z= Ar, Kr, Xe; X = Cl, Br, I and Y = H, F, OH) are investigated with ab initio calculations at the MP2/aug-cc-pVTZ level. Two different types of intermolecular interactions are present in these complexes, namely, aerogen bond (Z···N) and halogen bond (X···N). The formation mechanism and bonding properties of these complexes are analysed with molecular electrostatic potentials, quantum theory of atoms in molecules and non-covalent interaction index. It is found that the cooperativity energies in the ternary complexes are all negative; that is, the interaction energy of the ternary complex is greater (more negative) than the sum of the interaction energies of the corresponding binary systems. Also, the cooperativity energies increase with the increase of the interaction energies. The cooperative effects in the ternary complexes make a decrease in the total spin–spin coupling constants across the aerogen bonding, J(Z–N), which can be regarded as a proof for the reinforce of Z···N interactions in the ternary complexes with respect to the binary systems.     

Quasi-classical trajectory study of the isotope effect on the stereodynamics in the reaction H(2S)+CH(X2Π; v=0, j=1)→C(1D)+H2(X1Σg+)

The isotope effect on the stereodynamic properties in the title reaction is investigated by a quasi-classical trajectory (QCT) method on the 1¹A' potential energy surface at a collision energy of 23.06 kcal/mol. The angular distributions P(θ_r), P(ø_r), P(θ_r, ø_r), and the polarization-dependent generalized differential cross sections are calculated, which demonstrate the observable influences on the rotational polarization of the product by the isotopic substitution of H with D.     

配合物La（C5O3H3）3·C12H8N2·H2O的合成和表征

本以α－呋喃甲酸（Ｃ５Ｏ３Ｈ４）和邻菲罗啉（Ｃ１２Ｈ８Ｎ２）为配体,在乙醇８溶剂中与硝酸镧反应,合成了与稀土离子Ｌａ（Ⅲ）的三元混配配合物。经元素分析确定其配合物的组成为Ｌａ（Ｃ５Ｏ３Ｈ３）·Ｃ１２Ｈ８Ｎ２·Ｈ２Ｏ,同时还通过了ＩＲ、＾１ＨＮＭＲ、ＵＶ、ＴＧ－ＤＴＡ等谱光的测试与分析,表征了配合物的组成结构和性质。ＩＲ、＾１ＨＮＭＲ和ＵＶ谱的分析结果表明配体羧酸是以脱质子的酸根形式与中心稀土离子     

Proton conductivity in the layer compound H3OUO2AsO4·3H2O (HU As)

The proton conductivity in tetragonal H₃OUO₂AsO₄·(3-)H₂O has been measured above the transition temperature at 299 K. The conductivity, calorimetric and spectroscopic data depend on the water content and the transition is suggested to be a peritectic reaction setting free a small amount of solution, which stays strongly adsorbed between the layers of the structure and gives rise to the high conductivity.     

Eu3+:Ln2O2S(Ln=Lu,Y,Gd,La)晶体的角重迭参数计算

本文使用角重迭模型(AOM),针对Eu3+:Ln2O2S(Ln=Lu,Y,Gd,La)晶体系列,在考虑硫和氧两种不同格位的情况下,对f电子的全部四个角重迭参数eσ、eπ、eδ和eφ进行了计算,得到了一些基本规律,即中心离子与配位体之间的共价性大小次序为Lu～Y>Gd>La,并且Ln-O键的共价性要强于Ln-S键.     

Effect of electron-donating and electron-withdrawing atoms on the C–H…Y hydrogen bond in model X3CH…YZ (X = B,F; YZ = BF,CO, N2) complexes

A computational study of model complexes X₃CH…YZ (X = B, F; YZ = BF, CO, N₂) was undertaken to assess the effect of electron-donating and electron-withdrawing X atoms on the properties of the C–H…Y hydrogen bond. Sequential substitution of the B atoms in B₃CH by F atoms to produce F₃CH allowed for the elucidation of interesting trends in the corresponding hydrogen-bonded complexes. The dipole moments and the dipole moment derivative with respect to C–H bond displacement for the proton donors and the chemical hardness of the Y atom of the proton acceptor YZ were found to be useful parameters for understanding these trends. It was found that a positive dipole derivative favours red-shifted hydrogen bonds, whereas a negative dipole derivative favours blue-shifted hydrogen bonds. However, decreasing hardness of Y (which correlates with increasing intermolecular attraction) modifies the interaction such that either greater C–H bond extensions/red shifts or smaller C–H bond compressions/blue shifts are obtained.     

Ground state of the kagomé-like S=1/2 antiferromagnet volborthite Cu3V2O7(OH)2 x 2H2O

The volborthite compound is one of the very few realizations of S=1/2 quantum spins on a highly frustrated kagomé-like lattice. Low-T SQUID measurements reveal a broad magnetic transition below 2 K which is further confirmed by a peak in the 51V nuclear spin relaxation rate (1/T1) at 1.4 K +/- 0.2 K. Through 51V NMR, the ground state (GS) appears to be a mixture of different spin configurations, among which 20% corresponds to a well defined short-range order, possibly of the sqrt(3) x sqrt(3) type. While the freezing involves all the Cu2+ spins, only 40% of the copper moment is actually frozen which suggests that quantum fluctuations strongly renormalize the GS.     

CnH2n(n=2,3,4)与BX3(X=H,F,Cl)作用的DFT研究

用量子化学的密度泛函理论方法对BX3(X=H,F,Cl)与烯烃CnH2n(n=2,3,4)形成的复合物进行了研究,结果表明,复合物的构型皆为BX3位于烯烃π键的上方,并且偏向氢原子数较多的碳原子一侧.C-C双键中的π电子通过向BH3中B的空p轨道转移电子而形成复合物,但BF3和BCl3与烯烃分子只是通过微弱的分子间作用力结合,复合物的形成使分子的振动光谱随作用的强弱而出现一定的红移现象.     

Structures and stabilities of the donor–acceptor complexes HXPY (X=Al,B; Y=H,F, OH)

The optimized geometries, complexation energies, etc. of HXPY (X?=?Al, B; Y?=?H, F, OH) donor–acceptor complexes have been investigated at the B3LYP/6-311+G(d,p), MP2/6-311+G(d,p) and/or CCSD(T)/6-311+G(d,p) levels. The results show that HBPY (Y?=?H, F, OH) is more stable than the corresponding HAlPY (Y?=?H, F, OH), F (or OH) substitution on phosphorus results in decreasing complex stability, and the stronger the electron-attracting nature of the substitution atom, the more stable the complex. Moreover, the thermodynamic and kinetic properties of the formation reaction of these donor–acceptor complexes were also examined within the temperature range 200–800?K using the general statistical thermodynamics and Eyring transition state theory with Wigner correction. It is concluded that the formation of HBPY is thermodynamically favoured over that of the corresponding HAlPY, especially at low temperature, and is kinetically favoured over that of the relevant HAlPY (Y?=?H, F, OH), especially at high temperature.     

Si3Xn (X=C,O,N;n=1,2)团簇的密度泛函研究

使用密度泛函理论(DFT)的杂化密度泛函B3LYP方法在6-31G*基组水平上对Si3Xn(X=C,O,N;n=1,2)团簇各种可能的构型进行几何结构优化,预测了各团簇的最稳定结构.并对最稳定结构的电子结构、振动特性、成键特性和电荷特性等进行了理论研究.结果表明团簇的几何结构都是平面结构,通常Si3X2出现是Si-X键,较少出现X-X键;而Si3X中出现Si-X键和Si-Si键共存,Si3Xn(X=C,O,N;n=1,2)团簇的电荷布局分布表明这种电荷转移的作用使得团簇中所有X原子呈负电性,Si原子显正电性.处于不同位置的Si原子呈不同大小布局数,而且由于Si3X2的对称性,2个X负电性相同.     

Variation in the Luminescence Lifetimes of Eucl3·nH2O(N=0,L,2,3,6)

Eu³⁺ ion emission spectra and luminescence lifetimes were investigated for EuCl₃ -nH₂O (n=0,1,2,3,6). Each compound exhibited a characteristic set of emission bands and a specific luminescence lifetime. The number of water molecules and chloride ions coordinated to the Eu³⁺ ion in these materials was estimated from the observed lifetimes, spectroscopic implications, and expected lanthanide coordination numbers. Approximation of the observed luminescence decay constant for each material was possible through the use of arithmetic terms associated with both the complexed water molecules and the complexed chloride ions which make up the inner-coordination sphere of the Eu³⁺ ion.     

Cooperative interaction between π-hole and single-electron σ-hole interactions in O2S···NCX···CH3 and O2Se···NCX···CH3 complexes (X = F,Cl, Br and I)

Ab initio calculations are performed to analyse the cooperative effects between π-hole and single-electron σ-hole interactions in O₂S···NCX···CH₃ and O₂Se···NCX···CH₃ complexes, where X = F, Cl, Br and I. These effects are investigated in terms of geometric and energetic features of the complexes, which are computed by UMP2/aug-cc-pVTZ(-PP) method. Our results indicate that the shortening of the each π-hole bond distance in the complexes is dependent on the strength of the σ-hole interaction. The maximum and minimum energetic cooperativity values correspond to the most and least stable complexes studied in the present work. The cooperativity between both types of interaction is chiefly caused by the electrostatic effects. The topological analysis, based on the quantum theory of atoms in molecules, is used to characterise the interactions and analyse their enhancement with varying electron density at bond critical points.