NX(X=F,Cl,Br)分子结构与极化函数f轨道的作用

用密度泛函理论的Becke3LYP方法，计算了NX（X=F，Cl,Br）的激发态b1Σ＋ 和基态X3Σ－，并对比不含f轨道的基集合cc-pvDZ和6-311＋G与含f轨道的基集合6-311＋G(3df)的计算结果，发现极化函数f轨道对NCl和NBr的键长与谐振频率ωe有明显改进作用，即f轨道对成键有贡献，而f轨道对NF的Re和ωe则无明显作用.同时，基于能量共振转移的需要，用NF代替O2-I 红外激光系统的O2是不适宜的，而用NCl和NBr代替则是可能的.     

NX(a 1Δ, X=F、Cl、Br)分子结构与ωe～Re关联模型

基于不少双原子分子的稳定激发态系列中存在已知ωe而未给出Re的现象,本文提出了ωe～Reα=C的理论模型,对近60个双原子分子的光谱数据进行了论证,并与量子力学计算结果进行了比较.结果表明,该模型具有通用性与可靠性.结合NX(a 1Δ)替代O2(a 1Δg)的新激光系统可能性研究需要,应用CIS、B3LYP与MCSCF方法,在6-311＋g(3df)基水平计算了NX(X=F、Cl、Br)第一激发态（a 1Δ）的结构,导出了解析势能函数.     

活性氮反应产生激发态卤化氮实验研究

A new method for producing electronically excited nitrogen monohalides NX(b) (X=F,Cl,Br) is reported. The strong emission spectra of NBr(b1Σ+→X3Σ–) are observed when alkyl bromides (CHBr3, CH2Br2, C2H5Br, and C4H9Br) are added to a stream of active nitrogen, generated by a hollow-cathode discharge of N2, in a flowing afterglow system. Some tentative experiments show that the electronically excited NBr(b) is formed by means of metastable N2(A3Σu+) Electronic-to-Electronic energy transfer to NBr(X), which is from the reaction of N(4S) with alkyl bromides. The emission spectra of NCl(b1Σ+→X3Σ–) are obtained when CCl4 or SOCl2 is admitted into a flow of active nitrogen, but neither CHCl3 nor CH2Cl2 addition results in such an emission. It has been proposed that the origin of the excited NCl(b) is an energy transfer from N2 (A) to NCl(X), generated by the reaction of N(4S) with CCl3 (or SOCl2). Similar experiments are also carried out with SF6 as reagent of active nitrogen, or as mixture with N2 in the discharge. By recording fluorescence it was found that excited NF(b) is produced only under discharge through N2/SF6 mixture. The NF(b) state presumably arises from the energy transfer from N2(A) to NF(X), and the latter is generated from the abstraction of fluorine by N(4S) from SF5.     

Building und Reaktionen des Phosphanyliden-Phosphorans (tBu)2P?P = PX(tBu)2 (X = Br,Cl)

Formation and Reaction of the Phosphanylidene-phosphorane (tBu)₂P? P = PX(tBu)₂ (X = Br, Cl) The formation of (tBu)₂P? P = P(Br)tBu₂ 1 from [(tBu)₂P]₂PLi and BrH₂C? CH₂Br begins with an exchange of Li against Br and is then determined by the migration of Br from the secondary P atom in [(tBu)₂P]₂PBr 6 to the primary P in 1 . Similarly, (tBu)₂P? P = PC1(tBu)₂ 2 is obtained starting from PCl₃ and LiP(tBu)₂. The formation of Phospanylidene—phosporane is not influenced by the choice o the halogene substituent, but the presence of the tBu groups is strongly required. (tBu)₂P? P(Li)? P(SiMe₃)₂ e. g., yields (tBu)₂P? P(br)? P(SiMe₃)₂ with BrH₂C? CH₂Br; however neither this nor (tBu)₂P? P(Cl)? P(SiMe₃)₂ do rearrange to a Phosphanylidene-phosphorane. The F₃C substituent could be neglected in this investigation as [(F₃C)₂P]₂P? SiMe₃ cannot be lithiated by means of BuLi. Compounds 1 and 2 display a charateristic temperature dependent behavior. While 1 at +20°C decomposes via the reactive intermediate (tBu)₂P? P to from the cyclophosphanes P₃[P(tBu)₂]₄, it gives crystals of [(tBu)₂P]₂P? p[P(tBu)₂]₂ at ?20°C (from a solution in toluene). Reacting 1 with tBuLi produces (tBu)₂P? P = P(H)tBu₂ 20 and (tBu)₂P? P(H)? P(tBu)₂ 14 . Initially, a transmetallation yield tBuBr and (tBu)₂ P? P=Pli(tBu)₂ 21 ,then LiBr and isobutene are eliminated and 20 is formed which can rearrange to produce 14 . Without the elimination of isobutene, 1 react with nBuLi to give 21 witch can be trapped with Me₃SiCl as (tBu)₂P? P(tBu)₂ 23 . The main product in in this reaction is however [(tBu)₂P]₂P? nBu 22 .     

C6F5X＋（X=Cl,Br,I,CH3）离子的理论研究

用DFT B3LYP方法及6-311G（d,p）,6-311＋G（d,p）和LanL2dz基组,对C6F5X＋（X=Cl,Br,I,CH3）阳离子做了理论研究,优化了它们的电子基态的构型,计算了对应分子的垂直电离势（VIP）和绝热电离势（AIP）.结果表明四种离子的构型的对称点群和对应分子相同,但构型参数有明显差别.B...     

Theoretical determination of the favorable mechanism of the reaction between AlX and HX (X = Br, Cl, and F)

The reaction mechanism between AlX and HX (X = Br, Cl, and F) have been characterized in detail using DFT as well as the ab initio method. The reaction yielding AlX₃ and molecular hydrogen was calculated to be highly exothermic. The present calculations also show that the possible routes to the trihalides species start more favorable with the primary insertion product AlX₂H than with the biadduct AlX(HX)₂ one.      

Synthesis,crystal structure,magnetism, and absorption spectra of A2UX5 Type Halides (A = K,Rb; X = Cl,Br, I)

The ternary uranium(III) halides A₂UX₅ (A = K, Rb; X = Cl, Br, I) have been prepared from the binary components AX and UX₃ in sealed tantalum containers. According to their Guinier X-ray powder patterns, they all crystallize with the K₂PrCl₅/Y₂HfS₅ type of structure. Lattice constants for ambient temperature are reported. Single-crystal structure refinemens were undertaken for K₂UI₅ and Rb₂UCl₅. Magnetic susceptibility data were recorded with a SQUID magnetometer from liquid helium to room temperature. One-dimensional (intrachain) and three-dimensional antiferromagnetic ordering occur at low temperatures dependent upon the U³⁺? U³⁺ distance. Absorption spectra were recorded between 4 000 and 28 000 cm^?1. They show f—f transitions typical for U³⁺ and, depending on the halide, very strong f—d transitions above 14 000 to 15 000 cm^?1, respectively.     

同核双卤分子X2(X=F,CI,Br,I)与C2H2相互作用本质的量子化学研究

用对称性匹配微扰理论(SAPT)对C2H2与X2(X=F,CI,Br,I)相互作用进行了量子化学研究.优化所得的4个稳定复合物相互作用能在-3.276 8～-10.639 5 kJ/mol之间.自然键轨道(NBO)理论分析表明,形成复合物分子间的电荷转移量都很少,在0.002 3～0.013 2之间.SAPT2能量分析显示,从F到I,静电能和诱导能先增大后减小,交换能和色散能逐渐增强,相互作用能依次增强.复合物稳定构型的相互作用能中静电能占主导作用,对吸引能的贡献比例在C2H2…F2中最大(57.3％),在C2H2…I2中最小(49.7％);其次为色散能,在吸引能中所占的比例在21.9％(C2H2…F2)～31.2％(C2H2…I2)之间;诱导能在吸引能中所占的比例最小,均小于20.7％.     

C_(56)X_(10)(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.     

苯-卤素(X2, X=F, Cl, Br, I)相互作用本质的对称性匹配微扰理论研究

在MP2水平下对被定义为"电荷转移复合物(CTC)"的苯(C6H6)-卤素分子X2(X＝F, Cl, Br, I)相互作用体系进行了量子化学研究. 在优化所得C6H6-X2(X＝F, Cl, Br, I)复合物的平衡几何结构中, 卤素分子X2接近垂直指向苯环上碳-碳双键的中心. 自然键轨道(NBO)分析结果表明, 苯-卤素体系中电荷转移的数量很少. 对称性匹配微扰理论(Symmetry-adapted perturbation theory, SAPT) 能量分解结果显示, 在4个复合物体系中, 静电作用的贡献相对较小(只占总吸引作用的20%左右), 对于C6H6-F2体系, 色散作用是其主要吸引作用, 对于C6H6-Cl2, C6H6-Br2和C6H6-I2 体系, 诱导作用则是其主要的吸引作用, 从F到I, 色散作用逐渐减弱, 诱导作用逐渐增强, 表明在电子相关水平上将苯-卤素体系称为"电荷转移复合物"的说法并不确切.     

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.     

Structure and conformational stability of CH2CHCH2X (X=F, Cl and Br) molecules—post Hartree–Fock and density functional theory methods

The molecular structure and conformational stability of CH₂CHCH₂X (X=F, Cl and Br) molecules were studied using ab initio and density functional theory (DFT) methods. The molecular geometries of 3-fluoropropene were optimized employing BLYP and B3LYP levels of theory of DFT method implementing 6-311+G(d,p) basis set. The MP2/6-31G^*, BLYP and B3LYP levels of theory of ab initio and DFT methods were used to optimize the 3-chloropropene and 3-bromopropene molecules. The structural and physical parameters of the molecules are discussed with the available experimental values. The rotational potential energy surface of the above molecules were obtained at MP2/6-31G^* and B3LYP/6-311+G(d,p) levels of theory. The Fourier decomposition of the rotational potentials were analyzed. The HF/6-31G^* and MP2/6-31G^* levels of theory have predicted the cis conformer as the minimum energy structure for 3-fluoropropene, which is in agreement with the experimental values, whereas the BLYP/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels of theory reverses the order of conformation. The ΔE values calculated for 3-chloropropene at MP2/6-31G^*, BLYP/6-311+G(d,p) and B3LYP/6-311+G(d,p) levels of theory show that the gauche form is more stable than the cis form, which is in agreement with the experimental value. The same levels of theory have also predicted that the gauche form is stable than cis for 3-bromopropene molecule. The maximum hardness principle has been able to predict the stable conformer of 3-fluoropropene at HF/6-31G^* level of theory, but the same level of theory reverses the conformational stability of 3-chloropropene and 3-bromopropene molecules and MP2/6-31G^* level of theory predicted the stable conformer correctly.     

tBu2P?PP(X)tBu2-Ylide (X = Cl,Br, I) durch Halogenierung von [tBu2P]2P?SiMe3

tBu₂P? P?P(X)tBu₂ Ylides (X = Cl, Br, I) by Halogenation of [tBu₂P]₂P? SiMe₃ [tBu₂P]₂P? SiMe₃ 1 with halogenating agents as Br₂, I₂, Br-succinimide, CCl₄, CBr₄, CI₄ or C₂Cl₆ via cleavage of the Si? P bond in 1 produces the ylides tBu₂P? P?P(X)tBu₂ (X = Cl, Br, I). This proceeds independent from the formerly known pathway – [tBu₂P]₂PLi + 1,2-dibromoethane – and shows that the Li-phosphide must not be present as a necessary requirement for the formation of ylides.     

B−Hb←:X (X= N,O, P,S, F,Cl, Br) interactions: A density functional study

Density functional theory calculation on B H_b←:X interaction (X= N, O, P, S, F, Cl, Br) is performed. HOMO energy predicts the feasibility of such complexation. Steric and electronic effects play significant role on geometry of the complexes. Interaction energy suggests that the interaction is moderately strong (< 5.00 kcal mol⁻¹) in nature and the complexes are stable in both gas and solvent phase. Electron donating group on: X facilitates the interaction whereas electron withdrawing group impedes the same. MP2 and CCSD(T) calculations further confirm the suitability of ωB97X‐D and M06‐2X functional for studying such interactions. Dispersive interaction is the primary mode of interaction in stabilizing the complexes. ¹H NMR and IR study are also performed. Thermochemical analysis advocates exothermic nature of complexation.     

ChemInform Abstract: Metal-Metal Bonding and Charge Localization in (Ru2X9)n-, X: Cl or Br; n = 1, 2, 3, 4. A Spectroelectrochemical Study

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

HNCO与CX（X=F，Cl，Br）自由基反应机理的密度泛函理论研究

用量子化学密度泛函理论的B3LYP方法,在6-31+G~*水平上按BERNY能量梯度解 析全参数优化了HNCO与CX（X=F,Cl,Br）反应势能面上各驻点的几何构型,通过 振动频率分析确认了中间体和过渡态,内禀反应坐标（IRC）对反应物、中间体、 过渡态和产物的相关性予以证实,对各驻点进行了零点能校正（ZPE）在此基础上 计算了反应能垒。研究结果表明,与HNCO和其它小分子自由基反应不同,HNCO与 CX自由基反应首先发生分子间H原子迁移,随后N与CX的C（1）原子相互靠近成键并 生成较稳定的中间体,再发生N-C（2）键的断裂,完成N向C（1）上的迁移并进一 步解离为产物。反应按反应物→TS1→IM→TS2→产物通道进行。反应为放热反应。     

The performance of density functional theory for LnF (Ln=Nd,Eu, Gd,Yb) and YbH

Different density functional theory (DFT) functionals have been evaluated by studying geometries and bond strengths of YbH, YbF, EuF, GdF, and NdF and compared with accurate CCSD(T) results and, when available, experiment. The agreement between the CCSD(T) results and experiment, when available, is good. The agreement is also good between bond strengths calculated at the DFT level using relativistic effective core potentials and the CCSD(T) results. However, the all-electron ADF calculations systematically overestimate binding energies. The geometries obtained by both the all-electron and the effective-core-potential-based DFT calculations are generally in good agreement with the CCSD(T) results.Contribution to the Björn Roos Honorary Issue     

Chemistry of ruthenium in N2P2X2 (X = Cl, Br) coordination sphere: Synthesis, characterization and reactivities

Reaction of 2-(phenylazo)pyridine (pap) with [Ru(PPh₃)₃X₂] (X = Cl, Br) in dichloromethane solution affords [Ru(PPh₃)₂(pap)X₂]. These diamagnetic complexes exhibit a weakdd transition and two intense MLCT transitions in the visible region. In dichloromethane solution they display a one-electron reduction of pap near − 0.90 V vs SCE and a reversible ruthenium(II)-ruthenium(III) oxidation near 0.70 V vs SCE. The [Ru^III(PPh₃)₂(pap)Cl₂]⁺ complex cation, generated by coulometric oxidation of [Ru(PPh₃)₂(pap)Cl₂], shows two intense LMCT transitions in the visible region. It oxidizes N,N-dimethylaniline and [Ru^II(bpy)₂Cl₂] (bpy = 2,2′-bipyridine) to produce N,N,N′,N′-tetramethylbenzidine and [Ru^III(bpy)₂Cl₂]⁺ respectively. Reaction of [Ru(PPh₃)₂(pap)X₂] with Ag⁺ in ethanol produces [Ru(PPh₃)₂(pap)(EtOH)₂]²⁺ which upon further reaction with L (L = pap, bpy, acetylacetonate ion(acac⁻) and oxalate ion (ox²⁻)) gives complexes of type [Ru(PPh₃)₂(pap)(L)]ⁿ⁺ (n = 0, 1, 2). All these diamagnetic complexes show a weakdd transition and several intense MLCT transitions in the visible region. The ruthenium(II)-ruthenium(III) oxidation potential decreases in the order (of L): pap > bpy > acac⁻ > ox²⁻. Reductions of the coordinated pap and bpy are also observed.     

难熔固体MX(M=Sc,Ti,V;X=C,N,O)电子结构和力学性质的密度泛函研究

采用密度泛函方法对MX(M=Sc,Ti,V;X=C,N,O)固体的体相电子结构和力学性质进行了系统研究.计算结果表明,对于金属原子相同的同一系列化合物,氮化物具有最大的体模量;进一步的研究可知,随着外界压力的增大,化合物由NaCl构型向CsCl构型转变由易到难的顺序依次是氧化物、氮化物和碳化物.本文还首次用密度泛函方法系统地计算了各化合物的能带结构和态密度,并对该类型化合物的导电性能进行了探讨.     

锗烯X2Ge(X=H、CH3、F、Cl、Br)与乙烯环加成反应的量子化学研究

利用量子化学密度泛函理论的B3LYP方法,在6-311G**的水平上,对锗烯X2Ge(X=H、CH3、F、Cl、Br)与C2H4的环加成反应进行了计算研究.结果表明,锗烯的基态是单重态,取代基的电负性越强,单-三态的能量差越大;控制反应的因素是电子效应,而不是立体效应;取代基的电负性越强,反应的活化能越高,放热越少;该反应由两步组成,第一步生成中间配合物,是一个无势垒的放热过程,第二步经过渡态生成产物.