Chemical dynamics of the CH(X2Π) + C2H4(X1A1g), CH(X2Π) + C2D4(X1A1g), and CD(X2Π) + C2H4(X1A1g) reactions studied under single collision conditions

The crossed beam reactions of the methylidyne radical with ethylene (CH(X(2)Π) + C(2)H(4)(X(1)A(1g))), methylidyne with D4-ethylene (CH(X(2)Π) + C(2)D(4)(X(1)A(1g))), and D1-methylidyne with ethylene (CD(X(2)Π) + C(2)H(4)(X(1)A(1g))) were conducted at nominal collision energies of 17-18 kJ mol(-1) to untangle the chemical dynamics involved in the formation of distinct C(3)H(4) isomers methylacetylene (CH(3)CCH), allene (H(2)CCCH(2)), and cyclopropene (c-C(3)H(4)) via C(3)H(5) intermediates. By tracing the atomic hydrogen and deuterium loss pathways, our experimental data suggest indirect scattering dynamics and an initial addition of the (D1)-methylidyne radical to the carbon-carbon double bond of the (D4)-ethylene reactant forming a cyclopropyl radical intermediate (c-C(3)H(5)/c-C(3)D(4)H/c-C(3)H(4)D). The latter was found to ring-open to the allyl radical (H(2)CCHCH(2)/D(2)CCHCD(2)/H(2)CCDCH(2)). This intermediate was found to be long lived with life times of at least five times its rotational period and decomposed via atomic hydrogen/deuterium loss from the central carbon atom (C2) to form allene via a rather loose exit transition state in an overall strongly exoergic reaction. Based on the experiments with partially deuterated reactants, no compelling evidence could be provided to support the formation of the cyclopropene and methylacetylene isomers under single collision conditions. Likewise, hydrogen/deuterium shifts in the allyl radical intermediates or an initial insertion of the (D1)-methylidyne radical into the carbon-hydrogen/deuterium bond of the (D4)-ethylene reactant were found to be-if at all-of minor importance. Our experiments propose that in hydrocarbon-rich atmospheres of planets and their moons such as Saturn's satellite Titan, the reaction of methylidyne radicals should lead predominantly to the hitherto elusive allene molecule in these reducing environments.     

CH(X2∏)+N2O的反应机理研究

在G2(B3LYP/MP2/CC)理论水平上研究了CH(X2∏)自由基与氧化二氮(NNO)分子的反应.计算了反应体系的最低二重态势能面上各驻点的构型参数、振动频率和能量,揭示了此反应存在两种机理和六个通道其中HC和NNO复合,生成中间体HC(N)NO,解离得到产物HCN+NO,这是最主要的通道之一;HC插入NO键,克服38.9 KJ/mol的势垒,产生富能的中间体HC(O)NN,预测了五个反应通道,其中主要反应通道为:NN+HCO.     

Darstellung und struktur von Cp2ZrX2 und [Cp2Zr(X)(H2O)2]+ X−(X = toluolsulfonat)

Cp₂Zr(C₇H₇SO₃)₂ (C) can be prepared from Cp₂ZrCl₂ and silver toluenesulfonate in acetonitrile. Reaction of C with H₂O gives the ionic 18-electron species [Cp₂Zr(C₇H₇SO₃)(H₂O)₂]⁺ C₇H₇SO₃⁻ (D). The structures of both complexes have been determined by X-ray analyses. The Cp₂Zr units in C and D have the usual bent metallocene structure. The metal-bonded O atoms of the three additional ligands in D lie in a plane bisecting the plane of the Cp ligands, the C₇H₇SO₃ group being symmetrically flanked by the H₂O ligands. The H₂OZrOH₂ angle is 148°. On the other hand, the OZrO angle of 90° in C is relatively small for a Cp₂ZrX₂ compound.     

Crossed beam reactions of methylidyne [CH(X2Π)] with D2-acetylene [C2D2(X1Σg(+))] and of D1-methylidyne [CD(X2Π)] with acetylene [C2H2(X1Σg(+))

The crossed molecular beam reactions of ground state methylidyne, CH(X(2)Π), with D2-acetylene, C(2)D(2)(X(1)Σ(g)(+)), and of D1-methylidyne, CD(X(2)Π), with acetylene, C(2)H(2)(X(1)Σ(g)(+)), were conducted under single collision conditions at a collision energy of 17 kJ mol(-1). Four competing reaction channels were identified in each system following atomic 'hydrogen' (H/D) and molecular 'hydrogen' (H(2)/D(2)/HD) losses. The reaction dynamics were found to be indirect via complex formation and were initiated by two barrierless-addition pathways of methylidyne/D1-methylidyne to one and to both carbon atoms of the D2-acetylene/acetylene reactant yielding HCCDCD/DCCHCH and c-C(3)D(2)H/c-C(3)H(2)D collision complexes, respectively. The latter decomposed via atomic hydrogen/deuterium ejection to form the thermodynamically most stable cyclopropenylidene species (c-C(3)H(2), c-C(3)D(2), c-C(3)DH). On the other hand, the HCCDCD/DCCHCH adducts underwent hydrogen/deuterium shifts to form the propargyl radicals (HDCCCD, D(2)CCCH; HDCCCH, H(2)CCCD) followed by molecular 'hydrogen' losses within the rotational plane of the decomposing complex yielding l-C(3)H/l-C(3)D. Quantitatively, our crossed beam studies suggest a dominating atomic compared to molecular 'hydrogen' loss with fractions of 81 ± 23% vs. 19 ± 10% for the CD/C(2)H(2) and 87 ± 30% vs. 13 ± 4% for the CH/C(2)D(2) systems. The role of these reactions in the formation of interstellar isomers of C(3)H(2) and C(3)H is also discussed.     

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.     

Al(2Pu)+H2(X1∑+R)的分子反应动力学

基于多体展式方法所导出的AlH2(X 2A1)分析势能函数,用准经典的Monte-Carlo轨迹法对Al(2Pu)+H2(X1∑+R,v=j=0)的分子反应动力学过程进行了计算.结果表明,此反应的主产物为交换反应Al(2Pu)+H2(X1∑+R,v=j=0)→AlH(X1∑+R,v′,j′)+H(2Sg)的AlH(X1∑+,v′,j′),没有发现AlH2(X2A1)络合物.而从反应的反应截面σ1与相对平动能E1的关系发现,该反应为有阈能反应,阈能值为314 kJ@mol～.同时,由于Al的质量比氢的大,发生的是直接碰撞,产物散射角分布是向前散射的.     

State-to-state quantum dynamics of the N(4S) + OH(X2Π) → H(2S) + NO(X 2Π) reaction

Quantum state-to-state dynamics for the N((4)S) + OH(X(?2)Π) → H((2)S) + NO(X(?2)Π) reaction is reported on an accurate ab initio potential energy surface of the lowest triplet electronic state (a(3)A(")) of HNO∕HON. It was found that the reaction is dominated by long-lived resonances supported by the HNO and HON wells. Significant non-reactive scattering was observed, indicating substantial deviations from the statistical limit. Due to the large exothermicity of the reaction, the NO product has hot internal state distributions: its rotational state distribution is inverted and peaks near the highest accessible rotational level; and its vibrational state distribution extends to υ = 10 and decays monotonically with the vibrational quantum number. In particular, the predicted product vibrational distribution is in reasonably good agreement with experiment. The calculated differential cross section is dominated by scattering in both the forward and backward directions, consistent with the formation of reaction intermediates.     

Al(2~P_u) H_2(X1~∑_g~ )的分子反应动力学

基于多体展式方法所导出的ＡＩＨ_２（Ｘ ~２Ａ_１）分析势能函数,用准经典的Ｍｏｎｔｅ－Ｃａｒｌｏ轨迹法对ＡＩ（~２Ｐ_ｕ）＋Ｈ_２（Ｘ~１∑_ｇ~＋,ｖ＝ｊ＝０）的分子反应动力学过程进行了计算．结果表明,此反应的主产物为交换反应ＡＩ（~２Ｐ_ｕ）＋Ｈ_２（Ｘ~１∑_ｇ~＋ ｖ＝ｊ＝０）→ＡＩＨ（Ｘ ~１∑~＋,ｖ~＇,ｊ~＇）＋Ｈ（~２Ｓ_ｇ）的ＡＩＨ（Ｘ ~１∑~＋,ｖ~’,ｊ~’）,没有发现 ＡｌＨ_２（ Ｘ~２ Ａ_１）络合物．而从反应的反应截面σ_ｒ与相对平动能Ｅ_ｔ的关系发现,该反应为有阈能反应,阈能值为 ３１４ ＫＪ·ｍｏｌ~(－１)．同时,由于 ＡＩ的质量比氢的大,发生的是直接碰撞,产物散射角分布是向前散射的．     

碰撞能对K(2S)+HF(X1Σ+)→KF(X1Σ+)+H(2S)反应的影响

基于Sayós等构建的基态势能面, 运用准经典轨线方法对原子-分子反应K(²S)+HF(X¹∑⁺)→KF(X¹∑⁺)+ H(²S)的立体动力学性质进行了研究. 计算了该反应的极化微分反应截面、 两矢量k?j'相关分布函数P(θ_r)、 三矢量k?k'?j'相关分布函数P(?_r)和空间分布函数P(θ_r,?_r). 结果表明, 产物KF的转动角动量j′不仅在垂直于反应物相对速度矢量k的方向上有强烈的取向效应, 而且还定向于y轴的负方向, 转动角动量j′敏感地依赖于碰撞能.     

Tantalocene complexes as bidentate métalloligands: (C5Me5)(C5H4X)Ta(H2)(PPh2) (C5Me5) (C5H4X)Ta(CO) (PPh2) (X = PPh2, CH2CH2NMe2)

The synthesis of new bidentate métalloligands derived from tantalocene(C₅Me₅)(C₅H₄X)Ta(H₂)(PPh₂) (X = PPh₂, 2P; X = CH₂CH₂NMe₂2N) and (C₅Me₅)(C₅H₄X)Ta(CO)(PPh₂) 4(P,N) is described. When opposed to chromium unsaturated fragments the phosphino functionalised complexes 2P and 4P act as chelating bidentate ligands affording Ta(V) (C₅Me₅)(C₅H₄PPh₂)Ta(CH₂) (μ-PPh₂)Cr(CO)₄ or Ta(III) (C₅Me₅)(C₅H₄PPh₂)Ta(CO)(μ-PPh₂)Cr(CO)₄ bimetallic complexes. The same reaction carried out starting from 2N gives rise to a μ-phosphido, μ-hydrido dibridged complex Cp*(C₅H₄CH₂CH₂NMe₂)TaH(μ-H)(μ-PPh₂)Cr(CO)₄.     

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.     

[Pd(en)2Pd(en)2X2]4+n(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〕ｎ＾４＋（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。     

N(4S)+ NO(X2Π)→N2(X3Σg-)+O(3P) 反应的立体动力学研究

采用准经典轨线方法研究了在不同碰撞能下，碰撞反应N(4S)+NO(X2Π)→ N2(X3Σg- )+O(3P)在两个最低势能面3A 和 3A'上产物与反应物之间的矢量相关. 结果表明，对于不同的碰撞能，在两个势能面上反应产物的转动取向展示了不同的特征和趋势. 随着碰撞能的增加，发生在3A 势能面上的反应主要受外平面机理支配，而发生在 3A' 势能面上的反应倾向于受内平面机理支配. 这些差异来自于两个势能面的不同构型.     

Kinetics and Dynamics of the H(2S)+NO(X2Π)→N(4S)+OH(X2Π)Reaction:A Quasi-classical Trajectory Studyt

A quasi-classical trajectory study of the H(2S)+NO(X2Π)→N(4S)+OH(X2Π)reaction kinetics and dynamics is reported on an accu-rate potential energy surface.The tot...     

Torsional potentials and conformational structures in the halogen substituted molecules HOCCH2X,HOCCHX2, XOCCH2X,XOCCHX2, XH2CCOCH3, X2HCCOCH3, (XH2C)2CO, (X2HC)2CO,and (X3C)2CO (X = Cl,Br) as determined by molecular-mechanics calculations

Parameter values of the non-blonded atom⋯atom interaction Br⋯OC have been established from gas-phase data. Conformational energies, structures, torsional barrier heights and torsional force constants of the title compounds have been estimated. For BrOCCH₂Br, (Cl₃C)₂CO and (ClH₂C)₂CO the calculated results are compared with gas-phase observations. It is suggested that hexachloroacetone ought to be reinvestigated by electron diffraction.     

Al(2Pu)+H2(X1Σ+g)的分子反应动力学

基于多体展式方法所导出的ＡｌＨ２（Ｘ＾２Ａ１）分析势能函数,用准经典的Ｍｏｎｔｅ－Ｃａｒｌｏ轨迹法对Ａｌ（＾２Ｐｕ）＋Ｈ２（Ｘ＾１∑＾＋ｇ,ｕ＝ｊ＝０）的分子反应动力学过程进行了计算。结果表明,此反应的主产物为交换反应Ａｌ（＾２Ｐｕ）＋Ｈ２（Ｘ＾１∑＾＋ｇ,ｖ＝ｊ＝０）→ＡｌＨ（Ｘ＾１∑＾＋,Ｖ’,ｊ’）＋Ｈ（＾２Ｓｇ）的ＡｌＨ（Ｘ＾１∑＾＋,ｖ’,ｊ’）没有发现ＡｌＨ２（Ｘ＾２Ａ１）的络合物。而     

金属簇X (X=Pt-Au, Au-Au)负载在(3×2) TiO2(110)完整表面上的覆盖度效应

采用自旋极化密度泛函和广义梯度近似的方法并结合周期平板模型,探讨了不同覆盖度(θ)下双金属簇X (X=Pt-Au, Au-Au)在(3×2)TiO2(110)完整表面上的吸附行为.另外,在本文给出的所有覆盖度模式下(θ=1/6-1 ML),我们仅研究其基态构型.计算结果表明:当θ<1/2 ML时,金属簇X在TiO2(110)表面上吸附能随覆盖度的增加而增加;当θ>1/2 ML时,除了饱和覆盖度下,吸附能随覆盖度的增加而减小;当θ=1/2 ML时,吸附能最大.即使Pt-Au/TiO2体系的吸附能比Au-Au/TiO2体系的小,但相对于Au-Au簇, Pt-Au簇更容易在TiO2(110)表面上形成双金属单分子层.在半覆盖和全覆盖下, X簇的峰与TiO2的峰在-3.0 eV到费米能级之间产生明显重叠,表明簇与底物之间存在化学作用.且当覆盖度小时, X-TiO2相互作用是成簇的主要因素;随着覆盖度的增大, X-X原子间相互作用就逐渐变成了成簇的主要动力     

Comparison of the crystal structures of Co2(X 2O7)·2H2O,X=P and As

Summary Crystals of Co₂(X ₂O₇)·2H₂O,X=P/As were synthesized under hydrothermal conditions. Their crystal structures were determined by single crystal X-ray diffraction:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2)Å, =94.77(2)/94.74(2)°, space group P2₁/n,R=0.032/0.046,R _w=0.028/0.034 for 2423/2042 reflections and 131/119 variables. Within the twoXO₄ tetrahedra connected via a common corner to anX ₂O₇ group the average P-O bond lengths are approximately equal (1.540 and 1.543 Å), but As-O differs significantly (1.685 and 1.696 Å). A comparison with the isotypic Mn and Mg pyrophosphates shows a correlation between the ratio Me-O/X-O and the angle O-X-O.

---

Vergleich der Kristallstrukturen von Co₂(X ₂O₇)·2H₂O,X=P und As

Zusammenfassung Kristalle von Co₂(X ₂O₇)·2H₂O,X=P/As wurden unter Hydrothermalbedingungen synthetisiert. Ihre Kristallstrukturen wurden mittels Röntgenbeugung an Einkristallen bestimmt:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2) Å, =94.77(2)/97.74(2)°, Raumgruppe P2₁/n,R=0.032/0.046,R _w=0.028/0.034 für 2423/2042 Reflexe und 131/119 Variable. In den beiden über eine gemeinsame Ecke zuX ₂O₇-Gruppen verknüpftenXO₄-Tetraedern sind die mittleren P-O-Abstände ungefähr gleich (1.540 und 1.543 Å), hingegen differiert As-O signifikant (1.685 und 1.696 Å). Ein Vergleich mit den isotypen Mn- und Mg-Pyrophosphaten zeigt eine Korrelation zwischen dem Quotienten Me-O/X-O und dem WinkelX-O-X.

     

CH2(X 3B1)自由基与O2的反应

用时间分辨富里叶红外发射谱仪（ＴＲ－ＦＴＩＲＳ）研究了ＣＨ２（Ｘ＾３Ｂ１）自由基与Ｏ２反应的通道及产物的振动动态布居，基电子态自由基ＣＨ２（Ｘ＾３Ｂ１）由３５１ｎｍ紫外激光光解ＣＨ２ＣＯ生成，观测到振动发态反应产物ＣＯ（ｖ≤１０），ＣＯ２（ｖ３≤７）ＯＨ（Ｈ２Ｏ）和Ｈ２ＣＯ的红外发射，证实存在生成Ｈ２ＣＯ的通道，由光谱拟合得到不同时刻ＣＯ（ｖ）和ＣＯ２（ｖ３）的相对振动布居，发现ｖ＝４能级的布居数