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。     

Structures and bonding situation of Pb2X2 (X?=?H, F, Cl, Br and I)

Quantum chemical calculations using DFT (BP86) and ab initio methods (MP2, MP4 and CCSD(T)) have been carried out for the title compounds. The nature of the Pb?CPb interactions has been investigated with an energy decomposition analysis. The energy minimum structures of the halogen substituted Pb₂X₂ molecules possess a doubly bridged butterfly geometry A like the parent system Pb₂H₂. The unusual geometry can be explained with the interactions between PbX fragments in the X ²?? ground state which leads to one Pb?CPb electron-sharing ?? bond and two donor?Cacceptor bonds between the Pb?CX bonds as donor and vacant p(??) AOs of Pb. The energy difference between the equilibrium form A and the linear structure XPb??PbX (E) which is a second-order saddle point is much higher when X is a halogen atom than for X?=?H. This is because the a ⁴??^?????X ²?? excitation energies of PbX (X?=?F?CI) are higher than for PbH. The structural isomers B, D1, D2, E, F1, F2 and G of Pb₂X₂ are no minima on the potential energy surface.     

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.     

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...     

Substituent effects on the compounds CX1X2•− (X1, X2 = H, F, Cl, Br, I) from theoretical investigation

The electronic and molecular structures of mono- and dihalocarbene anions constructed by model CX¹X^2?? (X¹, X² = H, F, Cl, Br, I), as well as the corresponding carbenes CX¹X² and analogous silicon-anions SiX¹X^2??, have been studied in detail using the B3LYP, MP2, and QCISD(T) levels of theory. Our calculated findings suggest that stabilization of the compounds is associated with the size of the halogen substituent X, which is further confirmed by ionization energies, the spin density (S _d), and the second-order perturbative energies (E(2)). Besides, we have also explored the source of the anions’ proton affinity difference.     

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.     

Pressure-induced formation of molecular B2X4(μ-X)2 (X = Cl, Br, I) species

Boron(III) halides (BX(3), where X = F, Cl, Br, I) at ambient pressure conditions exist as strictly monomeric, trigonal-planar molecules. Using correlated ab initio calculations, the three heavier halides (X = Cl, Br, I) are shown to possess B(2)X(4)(μ-X)(2) local minima, isostructural with the diborane molecule. The calculated dissociation barrier of the B(2)I(4)(μ-I)(2) species [≈14 kJ/mol with CCSD(T)/cc-pVTZ] may be high enough to allow cryogenic isolation. The remaining dimer structures are more labile, with dissociation barriers of less than 6 kJ/mol. All three dimer species may be stabilized by application of external pressure. Periodic density functional theory calculations predict a new dimer-based P1 solid, which becomes more stable than the P6(3)/m monomer-derived solids at 5 (X = I) to 15 (X = Cl) GPa. Metadynamics simulations suggest that B(2)X(4)(μ-X)(2)-based solids are the kinetically preferred product of pressurization of the P6(3)/m solid.     

CX3NO2(X=F,Cl)分子结构的稳定性

分子CF_3NO_2(1)、CF_2CINO_2(2)、CFCl_2NO_2(3)和CCl_3NO_2(4)在光化学和大气化学中是一类重要的分子。虽然它们的许多性质被广泛研究,但是从理论上尤其是ab initio分子轨道法对它们分子结构和化学键的研究报导极少。本文在ab initio/STO-3G水平上,全构型优化,系统地研究了这类分子的结构和各种构型的稳定性,并与实验以及CX_3NO(X=F,Cl)的结构进行了比较。计算采用Gaussian-82程序。在VAX-8350计算机上完成。结果和讨论分子各种稳定构型的键长、键角、Hartree-Fock能量、电荷密度及偶极矩列于表1至表3。     

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。     

OXO (X=Cl,Br)与X (2P3/2)反应机理的理论研究

用密度泛函B3LYP/6-311+G^**和高级电子相关的组态相互作用QCISD(T)/6-311+G^**方法研究了OXO与X(²P_3/2)双自由基反应的微观机理.研究结果表明:该反应存在两个反应通道,产物分别为XO和X₂+O₂.由于形成产物XO的活化势垒较低,因而是主要反应通道,这与实验观察到的结果是一致的.而形成X₂+O₂的通道从动力学上看是不利的.     

Theoretical studies on the reactions OH + CH3COCCl2 X (X = F, Cl, Br)

Theoretical investigations are carried out on the title reactions by means of the direct dynamics method. The optimized geometries, frequencies and minimum energy path are obtained at the MP2/6-31 + G(d,p) level, and energetic information is further refined at the MC-QCISD (single-point) level. The rate constants for both reactions are calculated by the improved canonical variational transition state theory with the small-curvature tunneling correction in a wide temperature range 200–3,000 K. The theoretical rate constant is in good agreement with the available experimental data. Furthermore, the effects of different halogen substitution on the rate constants are also discussed.     

PO2X…PX3/PH2X(X=F,Cl, Br,CH3, NH2)复合物中π-hole磷键作用的电子密度拓扑分析

磷键作为一种新型的分子键合力,因在晶体工程和超分子合成等方面的重要作用而越来越多地引起科研工作者的广泛关注。本文采用量子化学从头算和电子密度拓扑分析等方法,在MP2/aug-cc-pVTZ理论水平上,对PO₂X…PX₃和PO₂X…PH₂X (X = F, Cl, Br, CH₃, NH₂) π型复合物的结构和磷键性质进行了理论研究。研究表明:π-hole磷键复合物存在A和B两种稳定构型,分别以P…P和P…X磷键作用为主。分子中原子(AIM)、非共价作用(NCI)、电子定域函数(ELF)及适应性自然密度划分(AdNDP)分析表明,不同取代基对该类磷键作用的性质产生很大影响:当取代基为给电子基(CH₃, NH₂)时,磷键具有明显的共价作用特征;当取代基为吸电子基(F, Cl, Br)时,构型和取代基不同的磷键分别表现为非共价、部分共价或共价作用特征。自然键轨道(NBO)分析指出,分子间磷键的Wiberg键级的数值越大,磷键的共价性越强,磷键的作用强度越大。构型B的电荷转移主要是PX₃/PH₂X中X原子上的孤对电子转移到PO₂X中π^*(P=O)反键空轨道。     

Synthesis and Crystal Structures of Three Ladder Distannoxane Dimers [（PhCH2）2（Cl）SnOSn（X）（CH2Ph）2]2（X=Cl,OMe,OEt）

Three distannoxane dimers[(PhCH2)2(Cl)SnOSn(X)(CH2Ph)2]2(X=Cl,OMe,OEt)were prepared by the hydrolytic reaction of (PhCH2)2SnCl2 with sodium alkoxides.The compounds are assigned tetranuclear distannoxane structures in solid state.which contain the so-called ladder arrangement with a central planar Sn2O2 four-membered ring.The endo-and exo-cyclic Sn atoms are both five-coordinate,and have distorted trigonal bipyramidal geometries.A variety of hydrolyses of(PhCH2)2SnCl2 were performed and these dimers were characterized by IR,^1H NMR spectroscopy and X-ray diffraction analysis.     

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.     

双核钯配合物Pd2L2和Pd2L2X2(L=Me2PCH2PMe2;X=F,Cl,Br,I,H)的量子化学理论研究

采用 ab initio HF,MP2方法和密度泛函理论方法,对Pd(0),Pd(Ⅰ)双核配合物Pd2L2和Pd2L2X2(L=Me2PCH2PMe2;X=F,Cl,Br,I,H)的儿何结构和电子结构进行了研究.研究表明Pd2L2中Pd原子间的相互作用丰要来自电子相关效应,Pd2L2X2中Pd原子问的相互作用则主要来自d轨道的成键作用.MP2方法和局域泛函Xa方法能对两类配合物的几何结构给予准确的描述.在Pd2L2中,Pd原子的4d电了组成一一对应的成键、反键轨道,轨道作用相互抵消使Pd原子间仅存在微弱的相互作用.x原子与Pd2L2的作用使Pd-Pd反键轨道电子占据数减少,成键作用加强.两类配合物的Pd-Pd键长与NAO键级之间存在很好的线性关系.还对Pd2L2和Pd2L2X2的低占据电子激发态进行了含时密度泛函理论计算,分析不同配合物的电子跃迁特征,并就卤素配体对Pd2L2X2光谱性质的影响进行了讨论.     

制Cl2,为什么要用浓盐酸

和强酸制弱酸,HCl NaCH3COO=NaCl CH3COOH,难溶物转化为更难溶物,AgCl NaI=NaCl AgI相同,氧化还原反应,如Cl2 2NaBr=2NaCl Br2,被氧化产物(Br2)的氧化性弱于使用的氧化剂(Cl2),被还原产物(NaCl)的还原性弱于原先的还原剂(NaBr)。显然,酸(碱)性强度、难溶的难溶程度、氧化性(还原性)倾向相差越大,以上诸反应越完全。     

Mixed Amidohalotantalates [Ta(NMe2)3X3]– (X = F,Cl)

Russian Journal of Coordination Chemistry - The anionic tantalum complex (ItBuH)[Ta(NMe2)3Cl3] (I) is synthesized by the reaction of [Ta(NMe2)3Cl2]2 with N-heterocyclic carbene ItBu and is isolated...     

Gas phase reactions of Cl2O with X−(D2O)n=0–4 (X = O,OD, O2, DO2, and O3)

The reactions of Cl₂O with the cluster ions X⁻(D₂O)_n=0–4 (X = O, OD, O₂, DO₂, and O₃) were studied in a He buffer gas at temperatures within the range 171–298 K and pressures of 0.27–0.51 Torr, using a flow-tube apparatus. All ions were found to react with Cl₂O at rates slower than predicted by the collision rate and the charge center was transferred from X⁻ to Cl⁻ or ClO⁻. The primary product ions Cl⁻(DOCl) and ClO⁻(DOCl) were observed to react further to produce the ions Cl₃O⁻ and Cl₃O₂⁻. The rate constants for the observed reactions are reported and the role that thermodynamics plays in determining possible reaction channels is discussed.     

Organophosphines in PtPCOX (X = N,Cl, S), PtPCNX (X = Cl,S, Br,I, As) and PtPCClX (X = S,I, As) derivatives: structural aspects

In this review are classified and analyzed structural parameters of almost 90 monomeric organoplatinum complexes with inner coordination spheres consisting of PtPCOX (X?=?N, Cl, S), PtPCNX (X?=?Cl, S, Br, I, As) and PtPCClX (X?=?S, I, As). These complexes crystallized in three crystal systems: orthorhombic (× 11), triclinic (× 32) and monoclinic (× 45). Distorted square planar arrangements about the Pt(II) atoms are provided by mono-, heterobi- and heterotridentate donor ligands. The chelating ligands create a wide variety of four-, five- and six-membered metallocyclic rings and the effects of both steric and electronic factors influence the L–Pt–L bite angles. There are wide variations in the trans-positions of the donor ligands. Two examples are classified as distortion isomers.     

Unexpected complexation of allylpseudothiohydantoin hydrochlorides towards CuX (X = Cl,NO3, ClO4, BF4, 1/2SiF6). The first known examples of joint CuI(Cl,ClO4) and CuI(Cl,BF4) π-complexes

By means of alternating current-electrochemical synthesis starting from a mixture of 2-imino-3-(prop-2-en-1-yl)-1,3-thiazolidin-4-one (3-allylpseudothiohydantoin, napt) and 2-allylamino-1,3-thiazol-4(5H)-one (allylaminopseudothiohydantoin, aapt) hydrochlorides and corresponding copper(II) salts five new π-complexes, [Cu(napt)Cl] (1), [Cu₂(aapt)₂Cl]NO₃ (2), [Cu₂(aapt)₂Cl]BF₄ (3), [Cu₂(aapt)₂Cl]ClO₄ (4) and [Cu₂(aapt)₂Cl]₂SiF₆·2H₂O (5), were obtained and studied by X-ray single crystal diffraction and IR-spectroscopy. Napt and aapt molecules are selectively coordinated to Cu⁺ depending on the anion type. In crystals of 1 and 5, the organic ligands are attached to the metal in a chelating N,(C=C)-bidentate mode. The aapt molecule in 2-4 acts as a tridentate chelating ligand, being coordinated to the copper(I) ion through the heterocyclic N atom, carbonyl O atom, and C=C bond of allyl group, forming an original cationic [Cu₂(aapt)₂Cl]⁺ fragment with both a bridging Cl^– ion and O atom of the C=O group. In the presence of the doubly charged SiF₆^2– anion, Cu(I) in 5 prefers to be bonded with two bridging Cl^– ions, rather than the C=O group, causing [Cu₂(aapt)₂Cl]⁺ units to associate into the infinite cationic chains. Crystals of 3 and 4 are the first known examples of the simultaneous BF₄^–/Cl^– or ClO₄^–/Cl^– participation in copper(I) π-complex formation.