Topological characterization of HXO2 (X = Cl, Br, I) isomerization

The isomerization reactions of HOOX --> HOXO --> HXO2 (X = Cl, Br, I) have been studied by using the density functional theory. The breakage and formation of the chemical bonds of the titled reactions have been discussed by the topological analysis method of electronic density. The calculated results show that there is a transitional structure of a three-membered ring on each of the isomerization reaction paths. The "energy transition state (ETS)" and the "structure transition state (STS)" in all of the studied reactions have been found. In all these reactions, the position of the structure transition state and the scope of the structure transition region correlate well with the reaction energy. The STS appears after the ETS in the exothermic reaction but it appears before the ETS in the endothermic reaction. The less reaction energy there is, the wider scope of the structure transition region.     

Vibrational studies of [Ni(II)(DIARS)2X]X, (DIARS=o-C6H4(As(CH3)2)2 and X=Cl, Br, I).

Infrared and laser Raman spectra of [Ni(II)(diars)2X]X, (X=Cl, Br and I) have been used as probes to determine the structures of chelated diarsine molecules. It has been observed that the effects of metal chelation and coordination geometry give rise to frequency shifts in these complexes. The variation in vibrational spectroscopic features indicates reduction in the symmetry of the complexes in the crystalline environment. The effect of halogen on the Ni-halogen stretching frequency of these square pyramidal complexes is not as significant as observed in the case of octahedral complexes.     

Unexpected isomerism in "[Pd(2,9-dimethylphenanthroline)X2]" (X = Cl, Br, I) complexes: a neutral and an ionic form exist

Complexes of composition "[Pd(2,9-dimethylphenanthroline)X(2)]" (X = Cl, Br, I) have long been known and they are used as precursors for the synthesis of other derivatives or as catalysts. In the previous literature, they have invariably been described as neutral square planar complexes, but we have found that a second ionic isomer also exists, having composition [Pd(Neoc)(2)X](2)[Pd(2)X(6)], and that the formation of this isomer occurs under a wider range of conditions than that of the neutral one. Retrospectively, the ionic isomer had surely been obtained in most previous reports even if formation of the neutral one was claimed.     

Fe+与CH3X（X=Cl,Br,I）反应的理论研究

铁及其复合物催化的C—X键功能化日益引起人们的重视.采用密度泛函理论(DFT),在B3LYP/def2-SVP水平下详细研究了Fe+与CH3X(X=Cl,Br,I)的反应活性和机理.计算结果表明标题反应存在两种反应机制,即插入机制和SN2机制.从机理上来看,在插入机理中,反应都始于Fe+离子从侧面进攻CH3X,生成产物FeX+和CH3;而在SN2机制中,反应则始于Fe+离子从背后进攻CH3X,生成产物3FeCH+和X.从我们的计算可以看出,四重态或六重态下的Fe+离子在C—X键活化中展现了截然不同的催化活性;在所有通道中,都以四重态为主导;SN2机制中相对较高的决速能垒使其丧失了竞争性.再者,计算表明在所有的插入机制中,所有通道都是放热的,而在SN2机制中,仅有X=I时,反应是放热的.此外,计算表明这些反应属于两态反应活性,两种机制中,在反应的入口和出口存在最小能量交叉点.此外,反应途径电子结构追踪分析表明自旋极化对能量影响较大,调控着反应采取的反应通道和主副产物比例.通过本文的理论研究,尤其是详细的电子结构分析,为铁催化剂活化C—X键和C—C耦联反应提供了线索和以铁为基的催化剂设计提供理论依据.     

Schwingungs-Raman-Spektren von Hexahalogenokomplexen von OsIV (X = Cl,I) und IrIV (X = Cl,Br) bei 80 K

Vibrational Raman Spectra of Hexahalo Complexes of Os^IV (X = Cl, I) and Ir^IV (X = Cl, Br) at 80 K The Resonance-Raman (RR) spectra of the tetrabutyl- resp. tetraethylammonium salts of [OsCl₆]^2?, [OsI₆]^2?, [IrCl₆]^2?, and [IrBr₆]^2? have been investigated with the excitation-lines of an Ar⁺ and Kr⁺ laser. Devices with a movable sample holder for low-temperature experiments (80 K) are described. The anormal intensities of some of the Ra-active fundamentals are attributed to the RR effect. As a rule the deformation vibration υ₅(T_2g) is RR enhanced if excited within a π—π*(dt_2g)-CT-transition and the stretching vibration υ₂(E_g) is RR-enhanced within a π—σ*(de_g)-CT-transition. The dispersion of the degree of depolarisation of the three Ra-active fundamentals of [IrBr₆]^2? demonstrates, that this rule cannot only be applicated to the symmetrical but also to the antisymmetrical part of the scattering tensor.     

[Pd(en)_2Pd(en)_2X_2]_n~(4 )(X=Cl,Br,Ⅰ)链的畸变研究

对一维卤桥过渡金属化合物[Pd（en）2Pd（en）2X2]n4 （X＝Cl,Br,I）应用量子化学从头算及EHT能带计算进行了研究,发现Peierls畸变的产生及程度取决于填充轨道能量的降低与核间及电子间相互作用,合理解释了[Pd（en）2Pd（en）2X2]n4 （M=Pt,Pd,Ni;X＝Cl,Br,I）化合物畸变及混合价的递变规律．分析了Peierls畸变的产生对能隙及混合价的影响,得出了[Pd（en）2Pd（en）2X2]n4 （X＝Cl,Br,I）体系Pd的电荷差δe与偏移长度d存在线性关系的规律．     

MX2(AsH3)2(M=Pd,Pt;X=Cl,Br,I)的含时密度泛函理论研究

采用密度泛函方法(B3LYP)优化了MX2(AsH3)2[M=Pd；X=Cl(1)，Br(2)，I(3)和M=Pt；X=Cl(4)，Br(5)，I(6)]的基态结构，得到的几何参数与实验结果符合．以基态几何为基础，将TD-DFT方法用于计算标题配合物的电子吸收光谱．研究结果表明，金属的dx2-y2与配体所组成的反键轨道为LUMO轨道，从而该类配合物具有d-d跃迁属性的吸收带；在多数跃迁过程中，配体也有较大的贡献．     

A complete series of copper(II) halide complexes (X = F, Cl, Br, I) with a novel Cu(II)-C(sp3) bond

A complete series of copper(ii) halide complexes [CuX(tptm)](X = F (), Cl (), Br (), I (); tptm = tris(2-pyridylthio)methyl) with a novel Cu(II)-C(sp(3)) bond has been prepared by the reactions of [Cu(tptm)(CH(3)CN)]PF(6)(.PF(6)) with corresponding halide sources of KF or n-Bu(4)NX (X = Cl, Br, I), and the trigonal bipyramidal structures have been confirmed by X-ray crystallography and/or EPR spectroscopy. The iodide complex easily liberates the iodide anion in acetonitrile forming the acetonitrile complex as a result. The EPR spectra of the complexes showed several superhyperfine structures that strongly indicated the presence of spin density on the halide ligands through the Cu-X bond. The results of DFT calculations essentially matched with the X-ray crystallographic and the EPR spectroscopic results. Cyclic voltammetry revealed a quasi-reversible reduction wave for Cu(II)/Cu(I) indicating a trigonal pyramidal coordination for Cu(I) states. A coincidence of the redox potential for all [CuX(tptm)](0/+) processes indicates that the main oxidation site in each complex is the tptm ligand.     

Ionization energies of LinX (n = 2, 3; X = Cl, Br, I) molecules

Molecules of Li(n)X (n = 2, 3; X = Cl, Br, I) were examined with a magnetic sector mass spectrometer by surface ionization using a triple rhenium filament impregnated with fullerene (C60). The ionization energies obtained for Li(2)Cl, Li(2)Br and Li(2)I molecules are 3.8 +/- 0.1, 3.9 +/- 0.1 and 4.0 +/- 0.1 eV, respectively. The first ionization energy of Li(2)Cl is documented, while there are no literature data for the ionization energies of Li(2)Br and Li(2)I. The molecules of Li(3)Cl, Li(3)Br and Li(3)I were detected experimentally for the first time with ionization energies of 4.0 +/- 0.1, 4.1 +/- 0.1 and 4.1 +/- 0.1 eV, respectively. The ionization energies of Li(n)X (n = 2, 3; X = Cl, Br, I) are in correlation with the theoretical prediction of their hyperlithiated configurations.     

Formation and characterization of the uranium methylidene complexes CH2 = UHX (X = F, Cl, and Br)

The reactions between uranium atoms and CH3X (X = F, Cl, and Br) molecules are investigated in a solid argon matrix. The major products formed on ultraviolet irradiation are the CH2=UHX methylidene complexes. DFT calculations predict these triplet ground-state structures to be stable and to have significant agostic interactions. Parallels between the uranium and analogous thorium methylidene complexes are discussed.     

35Cl,79Br,81Br,and127I NQR spectra of HgHal2·XCH2CH2X complexes,X = OCH3, SCH3, and N(CH3)2

Conclusions From the NQR spectra of the halides HgHal₂ -D (Hal = Cl, Br, or I; D = SCH₃CH₂CH₂SCH₃, N(CH₃)₂ CH₂CH₂N(CH₃)₂, or OCH₃CH₂CH₂OCH₃) it follows that in their complexing ability the sulfur, nitrogen, and oxygen atoms can be arranged in the order: S > N > I. A structure with equivalent halogens is realized in the considered complexes.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1895–1897, August, 1973.The authors consider it their duty to thank G. K. Semin for his valuable advice and interest in the work.     

Die Gadoliniumcarbidhalogenide Gd4C2X3 (X = Cl,Br)

The Gadolinium Carbide Halides, Gd₄C₂X₃ (X = Cl, Br) The compounds Gd₄C₂X₃ (X = Cl, Br) and Tb₄C₂Br₃ have been prepared by reaction of the metals (RE), REX₃, and C in sealed Ta capsules at 1 100° and 1 300°C, respectively. Monophasic samples of Gd₄C₂Br₃ and Tb₄C₂Br₃ were obtained by reacting stoichiometric mixtures of the starting materials for five days. The needle shaped crystals are bronze-coloured and sensitive to air and moisture. Gd₄C₂X₃ crystallizes in the space group Pnma (No. 62) with lattice constants a = 1 059.6(4), b = 368.4(1), c = 1 962.7(8) pm (Gd₄C₂Cl₃), a = 1 084.4(1), b = 373.0(1), c = 2 036.1(1) pm (Gd₄C₂Br₃). According to Guinier photographs, Tb₄C₂Br₃ is isotypic (a = 1 074.3(2), b = 370.6(1), c = 2 019.4(1) pm). In the crystal structure C is octahedrally coordinated by Gd. The Gd₆ octahedra are linked via common edges to form corrugated layers. The X-anions coordinate all free edges and corners of these layers and connect them via Xⁱ? Xⁱ contacts parallel [001]. Gd₄C₂Br₃ shows metallic conductivity. The magnetic susceptibility follows at high temperatures a Curie Weiss law with an effective moment of 7.95 μ_B. At temperatures below 50 K antiferromagnetic order is observed.     

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.     

Observation of adducts in the reaction of Cl atoms with XCH2I (X = H, CH3, Cl, Br, I) using cavity ring-down spectroscopy

The reactions of Cl atoms with XCH2I (X = H, CH3, Cl, Br, I) have been studied using cavity ring-down spectroscopy in 25-125 Torr total pressure of N2 diluent at 250 K. Formation of the XCH2I-Cl adduct is the dominant channel in all reactions. The visible absorption spectrum of the XCH2I-Cl adduct was recorded at 405-632 nm. Absorption cross-sections at 435 nm are as follows (in units of 10(-18) cm2 molecule(-1)): 12 for CH3I, 21 for CH3CH2I, 3.7 for CH2ICl, 7.1 for CH2IBr, and 3.7 for CH2I2. Rate constants for the reaction of Cl with CH3I were determined from rise profiles of the CH3I-Cl adduct. k(Cl + CH3I) increases from (0.4 +/- 0.1) x 10(-11) at 25 Torr to (2.0 +/- 0.3) x 10(-11) cm3 molecule(-1) s(-1) at 125 Torr of N2 diluent. There is no discernible reaction of the CH3I-Cl adduct with 5-10 Torr of O2. Evidence for the formation of an adduct following the reaction of Cl atoms with CF3I and CH3Br was sought but not found. Absorption attributable to the formation of the XCH2I-Cl adduct following the reaction of Cl atoms with XCH2I (X = H, CH3, Br, I) was measured as a function of temperature over the range 250-320 K.     

Halogen-hydride interaction between Z-X (Z = CN, NC; X = F, Cl, Br) and H-Mg-Y (Y = H, F, Cl, Br, CH3)

Halogen-hydride interactions between Z-X (Z = CN, NC and X = F, Cl, Br) as halogen donor and H-Mg-Y (Y = H, F, Cl, Br, CH(3)) as electron donor have been investigated through the use of Becke three-parameter hybrid exchange with Lee-Yang-Parr correlation (B3LYP), second-order M?ller-Plesset perturbation theory (MP2), and coupled-cluster single and double excitation (with triple excitations) [CCSD(T)] approaches. Geometry changes during the halogen-hydride interaction are accompanied by a mutual polarization of both partners with some charge transfer occurring from the electron donor subunit. Interaction energies computed at MP2 level vary from -1.23 to -2.99 kJ/mol for Z-F···H-Mg-Y complexes, indicating that the fluorine interactions are relatively very weak but not negligible. Instead, for chlorine- and bromine-containing complexes the interaction energies span from -5.78 to a maximum of -26.42 kJ/mol, which intimate that the interactions are comparable to conventional hydrogen bonding. Moreover, the calculated interaction energy was found to increase in magnitude with increasing positive electrostatic potential on the extension of Z-X bond. Analysis of geometric, vibrational frequency shift and the interaction energies indicates that, depending on the halogen, CN-X···H interactions are about 1.3-2.0 times stronger than NC-X···H interactions in which the halogen bonds to carbon. We also identified a clear dependence of the halogen-hydride bond strength on the electron-donating or -withdrawing effect of the substituent in the H-Mg-Y subunits. Furthermore, the electronic and structural properties of the resulting complexes have been unveiled by means of the atoms in molecules (AIM) and natural bond orbital (NBO) analyses. Finally, several correlative relationships between interaction energies and various properties such as binding distance, frequency shift, molecular electrostatic potential, and intermolecular density at bond critical point have been checked for all studied systems.     

Reactivity of the ReOX3(PPh3)2 complexes (X = Cl or Br) with Schiff bases

Summary The reactions of ReOX₃(PPh₃)₂ (X = CI or Br) withN-methylsalicylideneimine (Me-saIH),N-phenylsalicylideneimine (Ph-saIH),N,N-ethylenebis(salicyli(leneimine) [(SaIH)₂en] and 8-hvdroxyquinoline (Oxinell) are here reported. They give rise to the ReOX₂(Me-sal)PPh₂. ReOX-(Me-sal)₂, ReOX₂(Ph-sal)PPh₃, ReOX(Ph-sal),, Re₂O₂X₄-(Sal₂en)(PPh₃)₂, ReOX₂(Oxine)PPh, and ReOX(Oxine)₂ complexes.     

First emission studies of Tc2X8(2-) systems (X = Cl, Br)

The emission spectra of the solids [n-Bu(4)N](2)Tc(2)X(8) (X = Cl, Br) have been investigated at room temperature and 77 K. In each case, the emission originates in the (1)δ-δ* excited state, as with the rhenium homologues, but has a shorter lifetime.     

Microhydration of X2 gas (X = Cl, Br, and I): a theoretical study on X2.nH2O clusters (n = 1-8)

Structure and properties of hydrated clusters of halogen gas, X2.nH2O (X = Cl, Br, and I; n = 1-8) are presented following first principle based electronic structure theory, namely, BHHLYP density functional and second-order Moller-Plesset perturbation (MP2) methods. Several geometrical arrangements are considered as initial guess structures to look for the minimum energy equilibrium structures by applying the 6-311++G(d,p) set of the basis function. Results on X2-water clusters (X = Br and I) suggest that X2 exists as a charge separated ion pair, X+delta-X-delta in the hydrated clusters, X2.nH2O (n > or = 2). Though the optimized structures of Cl2.nH2O clusters look like X2.nH2O (X = Br and I) clusters, Cl2 does not exist as a charge separated ion pair in the presence of solvent water molecules. The calculated interaction energy between X2 and solvent water cluster increases from Cl2.nH2O to I2.nH2O clusters, suggesting solubility of gas-phase I2 in water to be a maximum among these three systems. Static and dynamic polarizabilities of hydrated X2 clusters, X2.nH2O, are calculated and observed to vary linearly with the size (n) of these water clusters with correlation coefficient >0.999. This suggests that the polarizability of the larger size hydrated clusters can be reliably predicted. Static and dynamic polarizabilities of these hydrated clusters grow exponentially with the frequency of an external applied field for a particular size (n) of hydrated cluster.     

The mechanism of C--X (X=F, Cl, Br, and I) bond activation in CX4 by a stabilized dialkylsilylene

The potential-energy surfaces for the abstraction and insertion reactions of dialkylsilylene with carbon tetrahalides (CX4) have been characterized in detail using density functional theory (B3LYP), including zero-point corrections. Four CX4 species, CF4, CCl(4), CBr4, and CI(4), were chosen as model reactants. The theoretical investigations described herein suggest that of the three possible reaction paths, the one-halogen-atom abstraction (X abstraction), the one-CX3-group abstraction (CX3 abstraction), and the insertion reaction, the X-abstraction reaction is the most favorable, with a very low activation energy. However, the insertion reaction can lead to the thermodynamically stable products. Moreover, for a given stable dialkylsilylene, the chemical reactivity has been found to increase in the order CF4相似文献