Theoretical studies of the reactions of Cl atoms with CF3CH2OCH n F(3−n) (n = 1, 2, 3)

This paper presents the theoretical studies of the reactions of Cl atoms with CF₃CH₂OCH₃, CF₃CH₂OCH₂F and CF₃CH₂OCHF₂ using an ab initio direct dynamics theory. The geometries and vibrational frequencies of the reactants, complexes, transition states and products are calculated at the MP2/6-31+(d,p) level. The minimum energy path is also calculated at same level. The MC-QCISD method is carried out for further refining the energetic information. The rate constants are evaluated with the canonical variational transition state theory (CVT) and CVT with small curvature tunneling contributions in the temperature range 200–1,500 K. The results are in good agreement with experimental values.     

Valence of elements in HgBa_2Ca_(n-1)Cu_nO_(2n+2+δ)(n=1, 2, 3, 4)

HgBa2Can-1CunO2n+2+( (n=1, 2, 3, 4) 1 are tetragonal with space group space P4/mmm. For n=1,2,3, nearly single-phase crystals were obtained, while for n=4, the sample was primarily a mixture of the n=3 and 4 phases. These materials also possessed the highest Tc values yet observed for any superconductors. In this paper, the valences of elements in the title compounds were calculated from bond valence sum method 2. The calculated bond covalency, valences of elements were summarized in Table …     

PdYn±(n=0, 1, 2, 3)分子离子的结构与稳定性

在Pd和Y原子相对论有效原子实势和基函数SDD下, 使用密度泛函理论B3LYP方法对PdYn±(n=0, 1, 2, 3)分子离子的势能曲线与稳定性进行计算研究, 结果表明, PdY分子和PdY−, PdY2−, PdY3−与PdY+分子离子的基态电子状态分别为X2Σ、X1Σ、X2Σ、X1Σ、X1Σ, 能稳定存在, 势能函数可用Murrell-Sorbie函数表达, 并计算得到相应的力常数与光谱数据; PdY2+和PdY3+分子离子的基态分别为X2Σ和X1Σ, 是亚稳定态, PdY3+分子离子的三重态是排斥态, 不能稳定存在.     

Structure and stability of AuXe n Z (n = 1–3, Z = −1, 0, +1) clusters

We have explored the structures and stabilities of AuXe _n ^Z (n = 1–3, Z = ?1, 0, +1) cluster series at CCSD(T) theoretical level. The electron affinities and ionization potentials are correlated to the HOMO–LUMO gaps. The role of the interaction was investigated using the natural bond orbital analysis.     

Vibrational spectra and electronic structure of 1-germatranol, 1,1-quasi-germatrandiole,and 1,1,1-hypogermatrantriole (HO)4−n Ge(OCH2CH2) n NR3−n (R = H,Me; n = 1–3)

IR spectra of 1-germatranol, 1,1-quasi-germatrandiole, 1,1,1-hypogermatrantriole with a general formula (HO)_4?n Ge(OCH₂CH₂) _n NR_3?n (n = 1–3) are obtained. At the B3LYP/aug-cc-pVDZ density functional level the equilibrium structures and vibrational spectra of these compounds along with their hydrogen-bonded dimers are calculated. Based on the calculations the band assignment is performed in the IR spectra of 1-germatranol, 1,1-quasi-germatrandiole, and 1,1,1-hypogermatrantriole. The existence of dimers is manifested in the IR spectra as the absence of bands in the frequency ranges characteristic of the bending vibrations of Ge-OH groups and the presence of bands in the vibrational range of hydrogen-bonded germatranyl groups.     

金属串配合物(n,m)[Cr3(PhPyF)4Cl2](n=2, 3, 4; m=2, 1, 0)的配位结构及其与电场的关系

应用密度泛函理论BP86 方法研究具有分子导线潜在应用的金属串配合物(n, m)[Cr₃(PhPyF)₄Cl₂](HPhPyF=N, N'-苯基吡啶基甲脒; n=2, 3, 4; m=2, 1, 0)的配位结构及其受电场作用的影响, n、m分别表示PhPyF-的苯环在左侧和在右侧的配体个数. 结果表明: (1) 零电场下, 四个PhPyF-的(2, 2)、(3, 1)和(4, 0)三种配位方式能量差别很小, 为竞争态, (2, 2)最稳定. (4, 0)结构中两端轴向配体Cl 均可与Cr 配位, 且Cl₄―Cr1 键比Cl5―Cr3键更强, 若作为分子器件可与电极结合, 这与(4, 0)[CuCuM(npa)₄Cl][PF₆](M=Pd, Pt; Hnpa=2-萘啶苯胺)靠近苯环一端的轴向配体无法与M配位不同. (2) 在(2, 2)、(3, 1)和(4, 0)中, Cr₃⁶⁺链均具有三中心三电子离域σ键, 但离域性逐渐减弱. 随四个PhPyF-配位方式趋于一致, 分子极性逐渐增大, 由Cl₄指向Cl5(Z)方向, Cr1的α自旋密度增大, Cr2 的β和Cr3 的α自旋密度减小. (3) 分子的几何结构和电子结构在电场下发生规律性变化, 在-Z方向电场作用下, (3, 1)、(4, 0)电子移动方向与极性方向相同, 使分子的键长、自旋密度、电荷和能隙变化显著性均大于Z方向电场, 且极性越大变化越显著, 有利于提高分子导电性.     

[n—CnH2n＋1NH3]2ZnCl4配合物相变研究

采用差示扫描量热法(DSC)和热重法(TG),研究了〔n-C_nH_(2n 1)NH_3〕_2ZnCl_4(n=9～12)配合物的热稳定性和固-固相变。该系列配合物的分解反应活化能和热稳定性基本上不随烷基链长而变化。配合物在280～370K存在固-固相变。相变数目表现出奇偶效应。相变热焓ΔH和熵ΔS随着烷基链长的增加而线性增大。主转变的峰值温度随烷基链的增长而升高,相应的相变被归属为烷基铵链的结构相变。     

CRYSTAL STRUCTURE OF 2, 4-DITHIONE-3-AMINO-1, 3, 2-OX-AZAPHOSPHORINEBENZO-2-THIONO PYRIDINIUM

<正> The structure of title compound [C7H6N2OPS3]-·[HNC5H5]+ was determined by x-ray diffraction. It belongs to monoclinic system with space group P21/a, a = 16.745(2), b= 8.563(2), c=21. 050(5)(?), β=93.32(1)°, V= 3013. 6(?)3, Z = 8, Mr = 341. 4, F (000) = 1536, Dc=1. 504 g. cm-3,μ= 53. 0 cm-1. The crystal is composed of discrete cations C5H5NH+ and anions CrH6N2OPS3-. There are two pairs of the cations and the anions in each asymmetric unit. The stability of the anion is increased by the formation of (d-p)π bonding involving the 3d orbital of the P atom and the lone electron pairs of the S atoms.     

Ab. initio calculations of Cl2SO ·nAICl3 complexes (n = 1, 2)

Fragments' of the potential energy surfaces (PES) for the SOCl₂ ·nAICl₃ (n = 1, 2) complexes were calculated by theab initio MO LCAO method using the RHF approximation for the STO-3G basis set and adding a 3d-AO for the S atom, as well as by the semiempirical MNDO method. Two local minima, assigned to the donor-acceptor complex Cl₂SO+AlCl₃ (la) and to Cl₃SOAlCl₂ (1b) were located on the PES atn = 1. Two local minima corresponding to two donor-acceptor complexes Cl₂SOAl₂Cl₆ and, were also located on the PES atn = 2. An analysis of the enthalpies of cation formation in the SOC1₂ +nAICl₃ (n = 1-3) systems calculated by theab initio method shows that the enthalpy of formation of the SOCl₊ cation atn = 2 is 17 kcal mol^–1 less than that atn = 1; the structure of the Cl₂SOAlCl₂ ⁺ cation with two strong electrophilic centers at the Al and S atoms becomes more favorable energetically atn = 3. The results of calculations for Cl₂SO ·nAICl₃ complexes by the MNDO method are in agreement with those obtained by theab initio method except for the geometry of complexes containing the Cl₃SO fragment and the charge values on the S atoms.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1116–1120, May, 1996.     

Existence of the homologous series of Y n Ba m Cu m + n O y (m = 2, 3, 5; n = 1, 2) oxides with the tetragonal and orthorhombic structures of YBa2Cu3O6 + δ

The phase composition of Y _x Ba_1?x CuO _y (x = 0.29?0.40) samples annealed in air (at 930?C990°C) and in an oxygen atmosphere (450?C800°C, P(O₂) = 101 kPa) was studied by X-ray powder diffraction, chemical analysis, electron diffraction, and elemental analysis in a transmission electron microscope. A considerable cation nonstoichiometry was discovered in particles having the tetragonal and orthorhombic structures of YBa₂Cu₃O_{6 + ??}. The variation range of particle compositions comprises matrix oxides of the Ba _m Cu _{m + n} O _y series with (Ba: Cu) 3: 5, 5: 8, 2: 3, and 5: 7, which in the presence of yttrium form the Y _n Ba _m Cu _{m + n} O _y series. Tetragonal oxides Y₂Ba₃Cu₅O _y (235), Y₃Ba₅Cu₈O _y (358), YBa₂Cu₃O _y (123), and Y₂Ba₅Cu₇O _y (257) are formed at the primary synthesis step in air and are preserved in an orthorhombic structure during short-term (1 h) oxygen annealing. Most particles of the 3: 5 and 5: 8 oxides are undersaturated with yttrium relative to the stoichiometry of the Y _n Ba _m Cu _{m + n} O _y series, those of the 2: 3 oxide correspond to this stoichiometry, and those of the 5: 7 oxide are supersaturated with yttrium over the stoichiometry. A trend is observed for the fractions of these oxides to change during long-term (5?C51 h) annealing in an oxygen atmosphere at 450°C and to the alternation of the dominant role of one of the four phases with the superconducting transition temperature T _c = 82, 85, 86, and 91 K. Each orthorhombic oxide undergoes structural transformations during oxygen annealing with a change in T _c. The coexistence of these oxides in the form of nanometer-sized domains does not allow their individual superstructures to be recognized.     

Syntheses,structures, and properties of transition metal complexes with 2-( n -pyridyl)benzimidazole ( n = 2, 3, and 4)

Three pyridylbenzimidazoles (2-PBIM, 3-PBIM, and 4-PBIM) have been prepared (2-PBIM: 2-(2-pyridyl)-benzimidazole, 3-PBIM: 2-(3-pyridyl)-benzimidazole, 4-PBIM: 2-(4-pyridyl)-benzimidazole). Reactions of several transition metals (Cd²⁺, Cu²⁺, Fe²⁺) with the three ligands gave four new coordination complexes, [(Cd)₂(2-PBIM)₂(CH₃COO)₄] (1), [Cu(3-PBIM)₂(CH₃COO)₂]?·?2H₂O (2), [Cu(4-PBIM)₂(CH₃COO)₂(H₂O)]?·?H₂O (3), and [Fe(4-PBIM)₂(Cl)₂(H₂O)₂] (4), respectively. These four complexes have been characterized by X-ray crystallography, IR spectroscopy, and UV absorption spectroscopy. Thermogravimetric properties of 2 and 4 were also measured. X-ray crystallographic studies reveal that these four complexes are very different, although the ligands are similar in structure. The role of hydrogen-bonding and π–π interactions in extending dimensionality of simple complexes has been discussed.     

HoCl~3-MCl~n体系相图的研究(M=Li,Mg, Ca,Pb; n=1, 2)

借助于DTA与X射线衍射法研究了HoCl~3-MCl~n(M=Li, Mg, Ca, Pb; n=1或2)二元体系相图, 发现HoCl~3-LiCl体系相图属固液异组成型, 有一化合物Li~3HoCl~6生成, 且在483℃有一相转变。其无变点分别为p(34.0mol%HoCl~3, 506℃)和e(50.5mol%HoCl~3, 452℃); 而HoCl~3-MgCl~2, CaCl~2, PbCl~2体系皆属简单低共熔型相图。其低共熔点e的组成与温度分别为: 50.0mol%HoCl~3(580℃)、49.0mol%HoCl~3(541℃)、37.0mol%HoCl~3(422℃)。HoCl~3-PbCl~2体系在固相下有一不稳定化合物PbHoCl~5生成, 在408℃分解, 同时探讨了RECl~3-LiCl相     

HoCl~3-MCl~n体系相图的研究(M=Li, Mg, Ca, Pb; n=1, 2)

借助于DTA与X射线衍射法研究了HoC_3-MCl_n(M=Li,Mg,Ca,Pb;n=1或2)二元体系相图.发现HoCl_3-LiCl体系相图属固液异组成型,有一化合物Li_3HoCl_6生成,且在483℃有一相转变.其无变点分别为p(34.0mol%HoCl_3,506℃)和e(50.5mol％HoCl_3,452℃); 而HoCl_3-MgCl_2,CaCl_2,PbCl_2。体系皆属简单低共熔型相图.其低共熔点e的组成与温度分别为:50.0mol％HoCl_3(580℃)、49.0mol％HoCl_3(541℃)和37.0mol％HoCl_3(422℃).HoCl_3-PbCl_2体系在固相下有一不稳定化合物PbHoCl_5生成,在408℃分解.同时探讨了RECl_3-LiCl相图的某些规律。     

Photoelectron imaging spectroscopy of S1(1B2u π,π*) benzene via 6(1)1n (n = 0-3) levels

We report resonance-enhanced two-photon ionization photo-electron spectroscopy of jet-cooled benzene via the 6(1)1(n) (n = 0-3) vibronic levels in S(1)((1)B(2u) π,π*) using a nanosecond UV laser and photoelectron imaging. The best energy resolution (ΔE/E) was 0.7%. The photoelectron spectrum from the S(1) 6(1)1(3) level (E(vib) = 3284 cm(-1)) in the channel three region exhibited a clear signature of intramolecular vibrational redistribution (IVR). The spectral features were consistent with picosecond zero kinetic energy photoelectron (ZEKE) spectra reported by Smith et al. [ J. Phys. Chem. 1995, 99, 1768]. The photoelectron angular anisotropy parameter β(2) was found to be negative in ionization from the 6(1)1(n) (n = 0-3) levels with photoelectron kinetic energies up to 5000 cm(-1). No influence of a shape resonance was identified.     

Synthesis,properties, and reactions of enantiomerically pure,chiral fluorous phosphines of the formula (menthyl)P(CH2CH2(CF2)n−1CF3)2 (n=6, 8)

Reactions of (menthyl)PH₂ and H₂CCHR_f6 (menthyl=1R,3R,4S; R_fn=(CF₂)_n−1CF₃) or H₂CCHR_f8 (AIBN, refluxing THF) give (menthyl)PH(CH₂CH₂R_fn) and then (menthyl)P(CH₂CH₂R_fn)₂ (n=6, 7; n=8, 8), but with purification or other difficulties at each stage. Reactions of (menthyl)PCl₂ with IMgCH₂CH₂R_fn give, under careful conditions, analytically pure 7 or 8 in 28–32% yields after distillation. Some R_fn(CH₂)₄R_fn also form. These represent the first chiral (and non-racemic) fluorous phosphines. Reactions of 7 or 8 with [Ir(COD)Cl]₂ and CO give trans-[(menthyl)P(CH₂CH₂R_fn)₂]₂Ir(Cl)(CO) (n=6, 71%; 8, 51%) as analytically pure yellow oils. Their IR ν_CO values show the donor/acceptor properties of 7 and 8 to be intermediate between those of P((CH₂)₃R_f8)₃ and P((CH₂)₄R_f8)₃. The CF₃C₆F₁₁:toluene partition coefficients of 7 and 8 (27°C, 78.4:21.6 and 93.7:6.3) are distinctly lower than those of P((CH₂)₂R_fn)₃ (n=6, 98.8:1.2; n=8, >99.7:<0.3), reflecting the replacement of a linear C₈–C₁₀ group that is ca. 75–80% fluorinated by a cyclic C₁₀ terpenyl group. Reactions of 7 or 8 with [Rh(COD)Cl]₂ give [(menthyl)P(CH₂CH₂R_fn)₂]Rh(Cl)(COD) (n=6, 69%; 8, 70%) as orange crystallizable oils.     

Synthesis of 1-alkoxy-3-methyl-1-triazene 2-oxides and 3, 3´-methylene-bis(1-alkoxy-3-methyl-1-triazene 2-oxides)

Russian Chemical Bulletin - A method for the synthesis of 1-alkoxy-3-methyl-1-triazene 2-oxides and their salts with alkali metals was developed. 3,...     

Synthesis of 3-Phenyl-6-formyl-3, 4-dihydro-2H-1, 3-benzoxazine

Benzoxazine is a novel class of thermosetting resins, which possesses lots of outstanding properties such as no by-products and near-zero shrinkage during polymerization as well as good molecular design flexibility1-2. Furthermore, polybenzoxazines (PBZs)…     

Polymeric (NO)3(N2O) n , (NO)3(N2O) n + , and (NO)3(N2O) n − : an interpretation of experimental observations

Semi-empirical and ab initio calculations are reported which provide a possible explanation for reported experimental results on 2-photon ionization of NO containing a few percent of N₂O, which found (NO)₃(N₂O) _n ^+or? clusters to be significantly more abundant than other (NO) _m (N₂O) _n products. It is found that the observed abundances of (NO)₃(N₂O) _n ionic clusters may be accounted for by the existence of covalent cyclic trimers of nitric oxide attached to oligomers of nitrous oxide. The extra stability of NO trimers in the observed clusters appears to arise from (NO) ₃ ⁺ rather than (NO)₃. Attachment of an (N₂O) _n side chain to (NO) ₃ ⁺ occurs exothermically. It is suggested that the addition of N₂O to cyclic-(NO) ₃ ⁺ might provide a means of making a polymer of nitrous oxide, which could have useful properties.     

A Computational NICS and 13C NMR Characterization of C60−n Si n Heterofullerenes (n = 1, 2, 6, 12, 20, 24, 30)

Density functional theory (DFT) calculations are performed for a representative set of low-energy structures of C_60-n Si _n heterofullerenes (n = 1, 2, 6, 12, 20, 24, 30) to investigate the effect of silicon doping on the electron structure of fullerene. The results show that chemical shielding (CS) parameters are so sensitive to the structural distortion made by outwardly relaxing silicon doped atoms from the fullerene surface which results in puckered Si-doped rings. As a result, the chemical shifts of the nearest carbon sites of silicon atoms considerably shift to downfield. Our survey shows that those first neighbors of silicon atoms which have minor ¹³C chemical shift belong to normal (un-puckered) rings. Meanwhile, the chemical shielding anisotropy (Δσ) parameter detects the effects of dopant so that Δσ values of the carbon atoms which are contributed to the Si–C bond are mainly larger than the others. Compensation between diatropic and paratropic ring currents lead to less negative NICS values at cage centers of Si-doped fullerenes than that of C₆₀ except C₅₈Si₂-b and C₅₄Si₆-b in which more negative NICS values may be attributed to more spherical geometries of their carbon cages.