基态N原子与CS2反应机理的理论研究

用密度泛函理论B3LYP/6 311+G 和高级电子相关偶合簇CCSD(T)/6 311+G 方法,计算研究了四重态氮原子与二硫化碳的反应,找到了分别形成CS+NS、NCS+S和CN+S2三个反应通道,优化搜索了各反应的过渡态,并用频率分析和内禀坐标法(IRC)验证了各鞍点构型和反应路径.在三个反应通道中,反应N+CS2→CS+NS由于具有较低的活化能而容易发生,其它两个通道活化能高很难发生,计算结果与实验结果一致.同时,对反应机理进行了详细的讨论.     

Ca+催化的N2O+CO反应机理的理论研究

采用B3LYP/cc-pVTZ理论水平系统研究了Ca+离子催化N2O+CO→N2+CO2反应的微观机理.反应分两步进行:第一步Ca+夺取N2O中的O原子有两条反应通道,其中优势通道为Ca+金属离子与N2O分子中O作用,形成线性分子复合物,活化N2O分子中的N-O键,之后的反应路径为O-N键断裂机理;第二步为CaO+金属...     

Theoretical study on the reaction of NbS~+(~3∑~-,~1Γ) with CO

Two possible reactions ofNbS+ (<3∑-,1ΓF) with CO in the gas phase have been studied by using B3LYP and CCSD(T) methods:the O/S exchange reaction (NbS+?" CO→NbO+?"CS) and the S-transfer reaction (NbS+?"CO→Nb+?"COS). The two reactions have a one-step mechanism. The barriers of the O/S exchange reaction on the triplet and singlet surfaces are 51.2 and 52.4 kcal/mol,respectively, and the barriers of the S-transfer reaction are 58.3 and 78.0 kcal/mol, respectively. The results indicate that the S-transfer and the O/S exchange reaction of the 3∑- ground state of NbS+ are competing, but, for the S-transfer reaction, the 1Γ exited state is more reactive. The differences between the reactions of NbS+ (3∑-, 1F) and VS+ (3∑-, 1Γ) are discussed.     

丙酮光解反应CH3COCH3hv→2CH3+CO产物CO振动态分布的理论研究

用从头算方法,在UHF/6-311G**水平上,对丙酮光解反应进行了研究,结果表明:基态丙酮(S0)不易发生解离;在光照下丙酮电子产生n→Π*跃迁,丙酮在激发态(T1)下易发生解离,即CH3COCH3(T1)→hvCH3+CH3CO(R1),乙酰基可以进一步发生热解反应,即:CH3CO→CH3+CO(R2). 对R2进一步获得了该反应的动态学信息(ωK,BKF,V0(S)),并据此计算了产物CO的振动态分布,获得了和实验值相一致的结果.     

氧原子与二硫化碳反应的机理

用从头计算法、内禀反应坐标和电子密度拓扑分析方法研究了3P态氧原子与二硫化碳的反应.找到了分别形成CS SO,S OCS和S2 CO三个反应通道上的极小点和过渡态.采用UHF/631G进行几何构型优化,并在UMP2/631G水平上进行能量校正.三个反应通道上的稳定点和过渡态都经内禀反应坐标(IRC)跟踪得以确认,并用电子密度拓扑分析方法考察了反应过程中化学键的变化.计算结果表明,反应过程中所有稳定点和过渡态都具有Cs对称性,即对每个反应通道而言在整个反应过程中分子始终保持在同一平面内.在三个反应通道中,第一个反应通道O CS2→CS SO由于具有较小的活化能而更容易发生,与实验结果相一致.文中对反应机理进行了较详细的讨论.     

氧气和CS自由基反应势能面的密度泛函理论研究

应用量子化学从头计算和密度泛函理论(DFT)对O_2和CS自由基的反应进行了研 究。在B3LYP/6-311G~(**)水平上计算出了各物种的优化构型、振动频率和零点振 动能(ZPVE)。各物种的总能量由CCSD（T）/6-311G~(**)//B3LYP/6-311G~(**)给出 ，并对总能量进行了零点能校正。计算结果表明：CS自由基中的C端沿着O_2的双键 中线方向进攻，进行加成反应，反应的第一步放出大量的热量(450 kJ/mol)，推动 反应继续进行，从稳定的中间体4(Cs)出发，反应主要通过O的相邻位置的迁移生成 P_1(CO+SO)和P_3(COS+O)；通过S的相邻位置的迁移生成了重要的反应复合物 (complex 1)，进一步离解为产物P_2(CO_2+S)。计算结果可以很好地解释反应机理 。     

Au+(1S, 3D)与N2O(1Σ+)反应机理的理论研究

采用密度泛函B3LYP方法, O和N用6-311+G*基组, Au+用赝势基组(8s7p6d)/[6s5p3d], 研究了Au+(1S, 3D)离子和N2O(1Σ+)分子的反应机理. 报道了在基态单重态和激发三重态势能面上各反应物、中间体和过渡态的构型特征及能量. 结果表明, 两个主反应通道Au+(1S)+ N2O(1Σ+)→1NA-Complex-1→1NA-TS1→1NA-Complex-2→1NA-Crossing→[3OAuNN]+和Au+(1S)+ N2O(1Σ+)→1NB-Complex→1NB-Crossing→[AuNN(1Σ+)]++O(3P)都需经过反应交叉势能面, 出现“系间窜越”. 用内禀坐标单点计算垂直激发态的方法确定了势能面交叉点, 并用含时密度泛函TD-B3LYP方法进一步探讨了自旋翻转机理.     

C3H2环丙烯基自由基与O(3P)反应机理的理论研究

本文用量子化学密度泛函方法对C3H2 (环丙烯基自由基)与O(3P)反应的机理进行了理论研究。在B3LYP/6-311++G**计算水平上优化了各驻点（过渡态,中间体,产物）的几何结构,在QCISD(T)/6-311++G**水平下计算了各物质的单点能量,在两种水平下计算了298K和600K时的能量。计算结果表明：C3H2 + O(3P) 反应可以生成P1 (C2H +HCO),P2 (C2H2 + CO) 和P3 (HC3O+H)三种产物。生成P1反应通道的能垒最低,即P1为主要产物,与实验的结果一致。产物P1可以通过路径：R→ IM1→ IM2→ P1获得。本文详细地讨论了C3H2 + O(3P) 的反应机理,并从理论上对实验结果进行了验证。研究结果有助于深入理解C3H2 + O(3P)反应机理以及C3H2在大气中的燃烧过程。     

·C2H3+O2→HC·O+H2CO 的密度泛函理论研究

应用密度泛函理论研究了@C2H3+O2→HC@O+H2CO的反应机理.在DFT(B3LYP/6-31G*)水平上对反应过程中所有反应物、中间体、过渡态和产物的几何构型进行优化,通过频率振动分析确认中间体和过渡态.计算IRC反应路径的能量,分析了中间体的异构化过程和各主要原子的自旋密度.     

HNCO+OH-→NH2+CO2反应理论研究

用从头算UHF/6-31G基组研究了异氰酸和羟基生成氨基和二氧化碳即HNCO+OH→NH2+CO2的反应机理.优化得到了反应途径上的过渡态和中间体,并通过振动分析对过渡态和中间体进行了确认.在UMP4/6-31G水平上计算了它们的能量,同时对零点能进行了较正.计算结果表明:此反应是多步反应,先后通过3个过渡态(TS1,TS2,TS3),2个内旋转位垒(PSI,TSII),4个中间体(IM1,IM2,IM3,IM4),其中,IM3→TS2这一步为整个反应的决速步骤,速控步的活化能为202.388lJ/mol.与异氰酸和羟基作用的另一反应通道(即HNCO+OH→H2O+NCO)的活化能(69.038kJ/mol)比较,可看出所研究反应通道为次要反应通道,这与实验结果是一致的.     

Sc2MgGa2 and Y2MgGa2

Scandium magnesium gallide, Sc₂MgGa₂, and yttrium magnesium gallide, Y₂MgGa₂, were synthesized from the corresponding elements by heating under an argon atmosphere in an induction furnace. These intermetallic compounds crystallize in the tetragonal Mo₂FeB₂‐type structure. All three crystallographically unique atoms occupy special positions and the site symmetries of (Sc/Y, Ga) and Mg are m2m and 4/m, respectively. The coordinations around Sc/Y, Mg and Ga are pentagonal (Sc/Y), tetragonal (Mg) and triangular (Ga) prisms, with four (Mg) or three (Ga) additional capping atoms leading to the coordination numbers [10], [8+4] and [6+3], respectively. The crystal structure of Sc₂MgGa₂ was determined from single‐crystal diffraction intensities and the isostructural Y₂MgGa₂ was identified from powder diffraction data.     

Zur Kenntnis der Dialkalimetalldichalkogenide β-Na2S2, K2S2, α-Rb2S2, β-Rb2S2, K2Se2, Rb2Se2, α-K2Te2, β-K2Te2 und Rb2Te2

On Dialkali Metal Dichalcogenides β-Na₂S₂, K₂S₂, α-Rb₂S₂, β-Rb₂S₂, K₂Se₂, Rb₂Se₂, α-K₂Te₂, β-K₂Te₂ and Rb₂Te₂ The first presentation of pure samples of α- and β-Rb₂S₂, α- and β-K₂Te₂, and Rb₂Te₂ is described. Using single crystals of K₂S₂ and K₂Se₂, received by ammonothermal synthesis, the structure of the Na₂O₂ type and by using single crystals of β-Na₂S₂ and β-K₂Te₂ the Li₂O₂ type structure will be refined. By combined investigations with temperature-dependent Guinier-, neutron diffraction-, thermal analysis, and Raman-spectroscopy the nature of the monotropic phase transition from the Na₂O₂ type to the Li₂O₂ type will be explained by means of the examples α-/β-Na₂S₂ and α-/β-K₂Te₂. A further case of dimorphic condition as well as the monotropic phase transition of α- and β-Rb₂S₂ is presented. The existing areas of the structure fields of the dialkali metal dichalcogenides are limited by the model of the polar covalence.     

Crystal Structures of [Bu2Sn(O2PPh2)2], [Ph2Sn(O2PPh2)2], and [PhClSn(O2PPh2)OMe]2. Raman Spectra of [Ph2Sn(O2PPh2)2] and [PhClSn(O2PPh2)OMe]2

[(n‐Bu)₂Sn(O₂PPh₂)₂] ( 1 ), and [Ph₂Sn(O₂PPh₂)₂] ( 2 ) have been synthesized by the reactions of R₂SnCl₂ (R=n‐Bu, Ph) with HO₂PPh₂ in Methanol. From the reaction of Ph₂SnCl₂ with diphenylphosphinic acid a third product [PhClSn(O₂PPh₂)OMe]₂ ( 3 ) could be isolated. X‐ray diffraction studies show 1 to crystallize in the monoclinic space group P2₁/c with a = 1303.7(1) pm, b = 2286.9(2) pm, c = 1063.1(1) pm, β = 94.383(6)°, and Z = 4. 2 crystallizes triclinic in the space group , the cell parameters being a = 1293.2(2) pm, b = 1478.5(4) pm, c = 1507.2(3) pm, α = 98.86(3)°, β = 109.63(2)°, γ = 114.88(2)°, and Z = 2. Both compounds form arrays of eight‐membered rings (SnOPO)₂ linked at the tin atoms to form chains of infinite length. The dimer 3 consists of a like ring, in which the tin atoms are bridged by methoxo groups. It crystallizes triclinic in space group with a = 946.4(1) pm, b = 963.7(1) pm, c = 1174.2(1) pm, α = 82.495(6)°, β = 66.451(6)°, γ = 74.922(6)°, and Z = 1 for the dimer. The Raman spectra of 2 and 3 are given and discussed.     

Electrochemical study of (NEt4)2Cl2FeS2MoS2 and (NEt4)2Cl2FeS2MoS2FeCl2

Summary The ability of [MoS₄]^2–, anions to be used as ligands for transition metal ions has been widely demonstrated, especially with Fe²⁺. The present study has been restricted to linear complexes such as (NEt₄)₂ [Cl₂FeS₂MoS₂] and (NEt₄)₂[Cl₂FeS₂MoS₂FeCl₂]. Their electrochemical properties are described: upon electrochemical reduction, these compounds yield MoS₂, as a black precipitate, and an iron complex in solution, assumed to be [SFeCl₂]^2–. The electrochemical reduction goes through two electron transfers, coupled with the breakdown of the molecular skeleton: a DISPl and an ECE mechanism. Depending on the solvent, the following equilibrium may be observed: [Cl₄Fe₂MoS₄]^2–[Cl₂FeMoS₄]^2–+FeCl₂. The equilibrium constant, K_D, was evaluated by differential pulse polarography. K_D is tightly related to the donor number of the solvent.     

Thermal decomposition of Me3SnO2PCl2, Me2Sn(O2PCl2)2 and Ph3SnO2PCl2

TG and DTA studies on Me₃SnO₂PCl₂, Me₂Sn(O₂PCl₂)₂ and Ph₃SnO₂PCl₂ were carried out under dynamic argon atmosphere. The results show that the decomposition proceeds in different stages leading to the formation of Sn₃(PO₄)₂ as a stable product. This compound was characterized by IR spectroscopy. Decomposition schemes involving reductive elimination reactions were proposed.     

The alkali hypophosphites KH2PO2, RbH2PO2 and CsH2PO2

The structures of the hypophosphites KH₂PO₂ (potassium hypophosphite), RbH₂PO₂ (rubidium hypophosphite) and CsH₂PO₂ (caesium hypophosphite) have been determined by single‐crystal X‐ray diffraction. The structures consist of layers of alkali cations and hypophosphite anions, with the latter bridging four cations within the same layer. The Rb and Cs hypophosphites are isomorphous.     

Syntheses,Spectroscopic Studies,and Crystal Structures of Me2Sn(O2PPh2)2, Ph2Pb(O2PMe2)2, and Ph2Pb(O2PPh2)2

Me₂Sn(O₂PPh₂)₂ ( 1 ), Ph₂Pb(O₂PMe₂)₂ ( 2 ), and Ph₂Pb(O₂PPh₂)₂ ( 3 ) have been synthesized by the reactions of Me₂SnCl₂ or Ph₃PbCl with the corresponding diorganophosphinic acid in methanol. X‐ray diffraction studies show that the diorganophosphinate groups behave as double bridges between the metal atoms leading to polymeric ring‐chain structures with M₂O₄P₂ (M = Pb, Sn) eight‐membered rings. The organic groups bonded to the metal atoms are in trans‐position in the resulting octahedral arrangement around the metal atoms. The IR and the mass spectra were reported and discussed.