Synthesis of molecular ferromagnetics [R3R′X]MCr(C2O4)3 (X = N,R = Bun,R′ = Prn,Et, Me; X = P,R = Ph,R′ = Bun; M = Mn,Fe, Co,Ni, Cu)

The synthesis, IR spectra, and the temperatures of the transition into a ferromagnetic state (T _c) of layered ferromagnetics [R₃RX[MCr(C₂O₄)₃ (M = Mn, Fe, Co, Cu, and Ni) with the [Ph₃BuP]⁺, [Bu₃RN]⁺ (R = Pr, Et, and Me) cations capable of subsequently changing the distances between metallooxalate layers have been considered. The temperatureT _c has been found to be independent of the size of the organic cation. It is believed that the determining factors in the transition to a ferromagnetic state are exchange interactions inside the metallooxalate layer.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2327–2330, September, 1996.     

C28X4（X=H,Cl）,CX4（X=H,Cl）的结构和电子光谱的理论研究

用ＩＮＤＯ法对Ｃ２８Ｘ４（Ｘ＝Ｈ，Ｃｌ）和ＣＸ４（Ｘ＝Ｈ，Ｃｌ）进行几何构型优化，得到Ｔｄ对称性的构型Ｃ２８Ｘ４有４种键、４种不等同原子，基态为稳定的闭壳层分子，以此构型为基础计算了上述分子的电子光谱，并预测Ｃ２８Ｘ４的电子光谱。     

LiY+NH2X(Y=F,Cl,Br,Br;X=F)反应机理的计算研究

一百多年来,无论从实验还是理论上,气相中碳原子上SN2的反应机理都已经得到了广泛的深入研究.近二十几年来,杂原子上的亲核取代反应由于其在生物有机及在人体代谢过程中所起的重要作用而逐渐引起人们的关注.氮原子上的SN2反应是近年来的研究热点,但其中的亲核试剂仅局限于阴离子[1].本文将研究对象扩展到离子对亲核取代反应[2].我们在B3LYP/6-311+G(d,p)水平上讨论了气相中LiY+NH2X(Y=F,Cl,Br,I;X=F)的反应机理,希望能为实验化学家提供有价值的信息.     

C70X2(X=H,F, Cl)的稳定性和电子光谱

用INDO方法研究C70H2四种异构体的稳定性, 表明其最稳定异构体为1, 9-C70H2和7, 8-C70H2, 两者能量差为16.3KJ.mol^-^1, 与实验值及ab initio计算值接近; 光谱计算表明, 其特征吸收峰与实验值一致。在此基础上预测C70F2和C70Cl2的稳定性和电子光谱, 表明C70F2四种异构体的稳定性顺序与C70H2一致, 而C70Cl2则以21, 42-异构体最为稳定。二者的电子光谱与C70H2极其相似只是在500nm以上有细微差别。     

C=X π-Systeme

Im Rahmen des Graduiertenkollegs “Hochreaktive Mehrfachbindungssysteme” hatten G. Erker und J. Grobe vom 16. bis 18. November 1994 schon zum zweiten Mal nach Münster eingeladen. “Organic and Inorganic Chemistry of Reactive C=X π-Systems” waren diesmal das Thema.     

Molecular assembly of dithiaparacyclophanes mediated by non-covalent X…X,X…Y and C–H…X (X,Y=Br,S, N) interactions

Regioselectivity for the 5,8,15,18-substituted isomer over the 5,8,14,17-isomer was observed in a series of mercaptan–bromide coupling reactions leading to the formation of 2,11-dithia[3.3]paracyclophanes. Their molecular assembly was established by X-ray crystallographic studies. In the crystal packing of these paracyclophanes, several types of non-covalent interactions including halogen–halogen interaction, halogen-bonding interaction, weak hydrogen-bonding interaction, etc. are observed in crystals 3a, 3b and 3c. There is evidence to indicate that weak non-covalent Br…Br, Br…S, Br…N, C–H…S, S…S and C–H…N interactions play an important role in governing their molecular assembly assumed in the solid state. The attractive interactions of Br…Br, Br…S and Br…N are also rationalised and supported in terms of the density functional theory calculations.

     

MX~4(M=Ti,Zr,Hf;X=Cl,Br)的电子结构研究

本文利用单电子非相对论Hartree-Fock-Slater和完全相对论Dirac-Fock-Slater两种离散变分局域密度泛函方法(DV-Xα), 对MX~4(M=Ti,Zr,Hf;X=Cl,Br)的电子基态和相应于低能UV光谱的激发态进行了计算, 结果与实验符合得较好。用Mulliken布居分析方法研究了分子的共价性质, 发现除HfBr~4外,相对论效应对金属与配体之间的键级影响很小。     

Si4X(X=C,N,O,Si,P,S)原子簇结构的理论研究

在密度泛函B3LYP/6-311G*水平上, 对具有C3v对称的Si4X (X = C, N, O, P, S)原子簇进行了几何构型优化计算, 并讨论它们的热力学稳定性、动力学活性、Mulliken布居、SiX键长、占据价轨道的对称性以及HOMO能级位置等周期递变规律。     

Theoretical Evidence of Aromaticity in X3 − (X = B, Al, Ga) Species

We investigated the electronic structure and chemical bonding of the B₃ ^–, Al₃ ^–, and Ga₃ ^– anions, and the gas phase NaB₃, NaAl₃, and NaGa₃ molecules. We found that the ground state of the neutral gas phase salts contains an equilateral triangular anion interacting with a Na⁺ cation. The B₃ ^–, Al₃ ^–, and Ga₃ ^– anions possess two delocalized electrons and are found to be aromatic. The triangular anions have been shown to be related to recently synthesized organometallic compound containing an aromatic -Ga₃ ^2– unit, but they are differ from them by four valence electrons. The reason for earlier appearance of the -orbital in the B₃ ^–, Al₃ ^–, and Ga₃ ^– anions is discussed.     

CH2X(X=H,F,Cl)与臭氧反应机理的量子化学研究

用量子化学UMP2方法,在6-311++G**基组水平上研究了CH2X(X=H,F,Cl)与臭氧反应机理,全参数优化了反应过程中反应物、中间体、过渡态和产物的几何构型,在UQCISD(T)/6-311++G**水平上计算了它们的能量,并对它们进行了振动分析,以确定中间体和过渡态的真实性.从CH2X(X=H,F,Cl)与O3的反应机理的研究结果看,它们与O3反应的活性都比较强,相对而言,活性大小顺序为CH2F＞CH3＞CH2Cl,也就是说,CH2F自由基与臭氧间的反应活性最强,对大气臭氧的损耗将是最大的.同时研究还发现CH2X(X=H,F,Cl)系列自由基与O3的反应都是强放热反应.     

CH_2=CH(XM)(X=S,Se,Te;M=H,Li,Na,K,Rb,Cs,-)的从头算研究

应用相对论有效势在ＭＰ２水平上对ＣＨ２ＣＨ（ＸＭ）（Ｘ＝Ｓ，Ｓｅ，Ｔｅ；Ｍ＝Ｈ，Ｌｉ，Ｎａ，Ｋ，Ｒｂ，Ｃｓ，－）进行了从头计算研究．结果表明，所研究的化合物都有平面式和非平面桥式两种构型．分析了碱金属离子对两可亲核底物ＣＨ２ＣＨＸ－（Ｘ＝Ｓ，Ｓｅ，Ｔｅ）离域化的影响，并用自然布局分析方法（ＮＰＡ）研究了电荷分布的变化，得出了有价值的结论．     

NbX(X=C,N,O)的能带结构研究

本文采用EHT近似下的紧束缚能带方法,计算了NbX(X=C,N,O)的能带结构。结果表明,它们的能带结构相近,Nb—X间存在较强的成键作用,传导电子主要具有Nb的4d特征,Nb—Nb键与超导电性相关,从C到N,Nb—Nb键共价性削弱,Tc提高。尽管计算所得NbO中Nb—Nb键强度介于NbC和NbN之间,但其实际Tc却比NbC和NbN的都低,这是NbO的空位效应所致,这一结果可从我们对有序缺陷的Nb_(0.75)O_(0.75)晶体能带结构的计算得到验证。     

非线性光学晶体LiBX_2(B=Ga,In;X=S,Se,Te)的研究

LiBX2(B=Ga,In;X=S,Se,Te)晶体具有宽的透光波段、足够大的双折射率、高的激光损伤阈值和小的双光子吸收系数等特性,是目前最具发展前景的中红外波段频率转换材料之一。本文从晶体结构入手,重点介绍了LiBX2晶体的光学性能、缺陷结构及晶体应用的最新研究成果。LiBX2晶体在二次谐波(SHG)相位匹配、差频产生(DFG)、光学参量放大(OPA)和光学参量振荡(OPO)等方面具有重要的应用前景。通过对晶体的透过光谱、吸收光谱、光致发光光谱和电子辐照的研究可以确定缺陷类型、缺陷浓度及最佳退火温度,分析晶体颜色与晶体组成和缺陷的关系。最后,提出LiBX2晶体今后应重点开展的研究方向,即获得更高光学质量的大尺寸晶体、降低晶体残余吸收和设计性能优良的抗反射膜(AR)。     

C56X10(X=F,Cl, Br,I)的结构稳定性和电子性质

采用密度泛函理论(DFT)中的广义梯度近似(GGA)方法对C56X10(X=F, Cl, Br, I)的结构稳定性和电子性质进行了计算研究. 结构稳定性计算表明: 对于C56X10(X=F, Cl, Br, I), 能隙、反应热、最大振动频率和最小振动频率都随着X原子序数的增加而减小, 表明C56X10(X=F, Cl, Br, I)的稳定性随着X原子序数的增加而逐渐降低, 其中C56F10最为稳定. 前人在实验上已成功合成出C56Cl10, 因此, 我们推测C56F10有望在实验上成功合成. 前线轨道计算发现, C56相邻的五边形公共顶点以及两个六边形-五边形-六边形公共顶点是笼子中化学活性最强的部位, 有利于卤族元素的外部吸附. 此外, 计算结果还显示, C56X10(X=F, Cl, Br, I)的电负性随着X原子序数的增大而逐渐减弱, C—X基团的电负性因位置的不同而不同.     

Exceedingly Facile Ph?X Activation (X=Cl,Br, I) with Ruthenium(II): Arresting Kinetics,Autocatalysis, and Mechanisms

[(Ph₃P)₃Ru(L)(H)₂] (where L=H₂ ( 1 ) in the presence of styrene, Ph₃P ( 3 ), and N₂ ( 4 )) cleave the Ph X bond (X=Cl, Br, I) at RT to give [(Ph₃P)₃RuH(X)] ( 2 ) and PhH. A combined experimental and DFT study points to [(Ph₃P)₃Ru(H)₂] as the reactive species generated upon spontaneous loss of L from 3 and 4 . The reaction of 3 with excess PhI displays striking kinetics which initially appears zeroth order in Ru. However mechanistic studies reveal that this is due to autocatalysis comprising two factors: 1) complex 2 , originating from the initial PhI activation with 3 , is roughly as reactive toward PhI as 3 itself; and 2) the Ph I bond cleavage with the just‐produced 2 gives rise to [(Ph₃P)₂RuI₂], which quickly comproportionates with the still‐present 3 to recover 2 . Both the initial and onward activation reactions involve PPh₃ dissociation, PhI coordination to Ru through I, rearrangement to a η²‐PhI intermediate, and Ph I oxidative addition.     

M2B5O9X∶Eu,Tb(M=Ca,Sr;X=Cl,Br)荧光体的光谱特征

利用Eu3+和Tb3+稀土离子之间存在电子组态共轭性的特征,将其双掺于同一基质中,由于电子转移而产生Eu2+,使Eu3+,Tb3+和Eu2+共存于同一体系中.在空气中合成了M2B5O9X∶Eu,Tb荧光粉,研究了其发光特征及影响作用.结果表明,Eu3+,Tb3+和Eu2+共存于同一基质中,且稀土离子的掺杂量对其光谱产生影响.     

ZH3,ZH+4及ZH4X(Z=N,P,As,Sb,Bi,X=F,Cl,Br,I)的结构与电子性质质

采用MP2/def2-TZVP理论方法考察了ZH3,ZH+4及ZH4X(Z=N,P,As,Sb,Bi,X=F, Cl, Br, I)的结构与电子性质。结果表明,随着氮族元素原子序数的递增,其氢化物(ZH3)中心原子杂化轨道中s成分减小,p成分逐渐增大,杂化轨道偏离平面的程度依次增大,导致NH3空间构型的最为“平面”,而BiH3最为“锥形”。尽管阳离子ZH+4由ZH3中Z的一个不等性sp3杂化轨道提供孤对电子与H+形成,但ZH+4中4个Z-H键等价,Z总体呈现等性sp3杂化。ZH4X均为C3v对称的四面体结构,ZH3与HX之间的作用驱动力来源于离子型的氢键(H3Z…H*-X)而非ZH+4与X－阴阳离子对(ZH+4X－)间的静电作用,H3Z…H*-X内的电子转移主要发生在轨道LP1(Z)与σ*(H*-X)之间。     

Photoelectron Spectroscopy and Structures of X−⋅⋅⋅CH2O (X=F,Cl, Br,I) Complexes

A combined experimental and theoretical approach has been used to investigate X⁻⋅⋅⋅CH₂O (X=F, Cl, Br, I) complexes in the gas phase. Photoelectron spectroscopy, in tandem with time-of-flight mass spectrometry, has been used to determine electron binding energies for the Cl⁻⋅⋅⋅CH₂O, Br⁻⋅⋅⋅CH₂O, and I⁻⋅⋅⋅CH₂O species. Additionally, high-level CCSD(T) calculations found a C_2v minimum for these three anion complexes, with predicted electron detachment energies in excellent agreement with the experimental photoelectron spectra. F⁻⋅⋅⋅CH₂O was also studied theoretically, with a C_s hydrogen-bonded complex found to be the global minimum. Calculations extended to neutral X⋅⋅⋅CH₂O complexes, with the results of potential interest to atmospheric CH₂O chemistry.     

XH3Y（X=C,Si,Ge;Y=Cl,Br,I,D）型气相分子合成技术

ＸＨ３Ｙ（Ｘ＝Ｃ，Ｓｉ，Ｇｅ；Ｙ＝Ｃｌ，Ｂｒ，Ｉ，Ｄ）型气相分子合成技术周泽义邓珂（中国科技大学选键化学开放实验室合肥２３００２６）谢立（安徽省计量测试研究所合肥２３００２２）关键词气相分子真空合成正交表中图分类号Ｏ６２１．２５５１ＩＶＸ的Ｃ、Ｓｉ、...     

Ab initio Valence Bond Study on AB-type Molecules,A Description for XH(X=L,Be,B,C,N,O,F) and XF(X=Li,Be,B)

Ab initio valence bond method is employed to quantitatively study the concepts of ionic resonance energy and ionicity of a chemical bond in the cases of hydrides XH(X=Li,Be,B,C,N,O,F) and fluorides XF(X=Li,Be,B),By establishing the relationship between resonance and stability,and comparing the calculated ionicities with Pauling‘s earlier estimations in the above diatomic molecules,the merits of Pauling‘s classical resonance theory were demonstrated at the ab initio level.