R2C＝GeH2和R2Ge＝CH2结构与成键特征的理论研究

用密度泛函理论(DFT), 在B3LYP/6-31＋G(d, p)水平上研究了取代基对二取代锗烯R₂Ge＝CH₂和R₂C＝GeH₂ [R＝H, OH, NH₂, SH, PH₂, F, Cl, Br, (NHCH)₂, CH₃, (CH)₂]的影响. 研究发现π供电子取代基在碳上时更能引起分子结构在锗端的锥型化. 碳原子上的π电子给予取代基的给电子效应越强, R₂C的单-三态能量差越大, π电子的反极化效应就越强, 使得化合物的结构在锗端发生的弯曲越明显, 从而使得弯曲结构更稳定. 和前人的计算相比, 碳上的给电子取代基对GeH₂结构影响大于它对SiH₂的影响.     

CH2CO＋CH2的多通道反应的理论研究

利用密度泛函(DFT)和自然键轨道理论(NBO)及高级电子耦合簇[CCSD(T)]和电子密度拓扑(AIM)方法, 对单重态和三重态CH₂与CH₂CO反应的微观机理进行了研究. 在B3LYP/6-311＋G(d,p)水平上优化了反应通道各驻点的几何构型. 在CCSD(T)/6-311＋G(d,p)水平上计算了各物种的单点能量, 并对总能量进行了校正. 计算表明, 单重态CH₂与CH₂CO的C—H键可发生插入反应, 与C＝C、C＝O可发生加成反应, 存在三条反应通道, 产物为CO和C₂H₄, 从能量变化和反应速控步骤能垒两方面考虑, 反应II更容易发生. 对反应通道中的关键点进行了自然键轨道及电子密度拓扑分析. 三重态CH₂与CH₂CO的反应存在三条反应通道, 一条是与C-H键的插入反应, 另一条是三重态CH₂与C＝C发生加成反应, 产物为CO和三重态C₂H₄, 通道II势垒较低, 更容易发生. 最后一条涉及双自由基的反应活化能最大, 最难发生.     

二维Co(nip)2(py)2(H2O)2配合物的水热合成, 晶体结构和热分解机理研究(nip＝5-硝基间苯二甲酸根, py＝吡啶)

用水热法以5-硝基间苯二甲酸和吡啶为配体合成并培养了Co(nip)₂(py)₂(H₂O)₂的单晶. 对单晶进行了X射线单晶衍射分析、元素分析、傅里叶变换红外光谱分析、差热分析和热重-微商热重分析. 该配合物晶体为单斜晶系, 属于P2(1)/c空间群. 晶胞参数为a＝1.1662(3) nm, b＝1.7734(4) nm, c＝0.6988(2) nm, β＝102.46(4)°, V＝1.4112(6) nm³, Z＝2, D_c＝1.585 Mg/m³, μ(Mo Kα)＝0.688 mm^－1. 所有晶体数据的R因子为: R₁＝0.1064, wR₂＝0.1270; 最终R因子[I＞2σ(I)]为: R₁＝0.0467, wR₂＝0.1008. X射线单晶衍射分析的结果表明, 依靠分子内氢键、分子间氢键、硝基氧之间的弱相互作用以及π-π堆积作用, 配合物分子被连成二维无限平面结构. 根据配合物的热分析结果, 配合物及热分析各阶段残渣的傅里叶变换红外光谱, 我们推测出了配合物的热分解机理.     

RN (R＝CH3, CH3CH2)异构化及脱氢反应的量子拓扑研究

利用量子化学从头算CASSCF方法在6-311＋G (d, p)基组水平上对单线态和三线态RN (R＝CH₃, CH₃CH₂)异构化反应及RN脱氢反应的微观机理进行了理论研究. 在MP2/6-311＋G (d, p)和CCSD/6-311＋G (d, p)水平上进行了单点能校正. 单态和三态势能面的交叉点(ISC)的存在清楚地说明了基态反应物³RN异构化为基态产物¹R'NH (R'＝CH₂, CH₃CH)的过程. 电子密度拓扑分析显示在整个异构化过程中有两种类型的结构过渡态: 单态反应通道为T型过渡态, 三态反应通道为环状过渡态. 单线态RN脱氢反应通道中“原子-分子键”的存在说明两个H原子是以H₂的形式从RN中脱去的.     

(NH2CH2CH2NH3)4[WⅤO2(OC6H4O)2]2(NH3CH2CH2NH3)·H2O的合成、晶体结构、EPR以及与同构物的比较

Cis-dioxo-catecholatotungsten(Ⅴ) complex (NH₂CH₂CH₂NH₃)₄[W^ⅤO₂(OC₆H₄O)₂]₂(NH₃CH₂CH₂NH₃)·H₂O (1) was synthesized at room temperature by the reaction of tetrabutyl ammonium decatungstate with catechol in the mixed solvent of CH₃OH, CH₃CN and NH₂CH₂CH₂NH₂. The crystal structure of complex was determined by X-ray diffraction structural analysis. The results show that complex belongs to monoclinic system with space group P2₁/c,a=0.712 8(3) nm, b=3.082 3(11) nm, c=0.982 8(4) nm, β=102.639(6)°, V=2.106 8(14) nm³, Z=2, R₁=0.062 8, wR₂=0.183 7. Compared the complex with its analogous complexes (NH₂CH₂CH₂NH₃)₃[Mo^ⅤO₂(OC₆H₄O)₂], it is found that the coordination structure of W have no changes in the processing of electron transfer of tungsten-containing enzymes from the result of the similarity of the EPR spectra of the complexes and flavoenzyme from milk. CCDC: 272937.     

CH3SOx (x＝0, 1)与三线态Oy (y＝1, 2, 3)反应机理的理论研究

采用B3LYP方法和6-311G(d, p)基组对CH₃S及其氧化后继物CH₃SO与O_y (y＝1, 2, 3)反应形成酸雨的微观机理进行了理论研究. 对反应势能面上的各驻点进行几何构型全优化. 振动分析和IRC计算证实了中间体和过渡态的真实性和相互连接关系. 找到了7条生成SO₂的反应途径, 其中CH₃S与O直接反应得到产物CH₃和SO最容易进行; CH₃S先与O₃反应, 其产物再与O₃反应得到CH₃SO₂, CH₃SO₂最后分解得到CH₃S和SO₂较容易进行, 其它的反应较难进行.     

磷叶立德CH2PH3和类磷叶立德自由基∙CHPH3优势构型和C—P键结构的研究

采用MP4/6-311++G(d,p)和B3LYP/6-311++G(d,p)对磷叶立德CH₂PH₃和类磷叶立德自由基∙CHPH₃进行构型优化，从电子密度拓扑分析的角度对C—P键的键结构进行了探讨。得到如下结论：类磷叶立德自由基和磷叶立德的C—P键性质类似，但磷叶立德中π键由两个电子形成，类磷叶立德自由基中π键由一个电子形成，所以前者的π性明显，而后者的π性不明显。类磷叶立德自由基中的这个单电子在碳原子附近，垂直于对称面的方向上运动，有p_(C→P)配键的特征，所以类磷叶立德自由基∙CHPH₃中的C—P键比相应的产物∙CH₂PH₂中的C—P键要弱一些。     

二维Co(nip)2(py)2(H2O)2配合物的水热合成, 晶体结构和热分解机理研究(nip＝5-硝基间苯二甲酸根, py＝吡啶)

用水热法以5-硝基间苯二甲酸和吡啶为配体合成并培养了Co(nip)₂(py)₂(H₂O)₂的单晶. 对单晶进行了X射线单晶衍射分析、元素分析、傅里叶变换红外光谱分析、差热分析和热重-微商热重分析. 该配合物晶体为单斜晶系, 属于P2(1)/c空间群. 晶胞参数为a＝1.1662(3) nm, b＝1.7734(4) nm, c＝0.6988(2) nm, β＝102.46(4)°, V＝1.4112(6) nm³, Z＝2, D_c＝1.585 Mg/m³, μ(Mo Kα)＝0.688 mm^－1. 所有晶体数据的R因子为: R₁＝0.1064, wR₂＝0.1270; 最终R因子[I＞2σ(I)]为: R₁＝0.0467, wR₂＝0.1008. X射线单晶衍射分析的结果表明, 依靠分子内氢键、分子间氢键、硝基氧之间的弱相互作用以及π-π堆积作用, 配合物分子被连成二维无限平面结构. 根据配合物的热分析结果, 配合物及热分析各阶段残渣的傅里叶变换红外光谱, 我们推测出了配合物的热分解机理.     

Au(II)化合物[Au(CH2)2PH2]2X2 (X＝F, Cl, Br, I)的量子化学理论研究

采用从头计算HF, MP2方法和密度泛函理论, 对Au(II)系列化合物[Au(CH₂)₂PH₂]₂X₂ (X＝F, Cl, Br, I)的几何结构、电子结构和振动频率进行了研究. 研究表明Au的5d和6s电子参与Au—Au以及Au—X之间的成键. Au—Au, Au—X键强烈的电子相关作用使HF方法不适于该体系的研究, BP86和B3LYP两种泛函给出较大的Au—Au和Au—X键长, 而MP2方法和局域的密度泛函方法则给出了合理的结构参数. 局域密度泛函方法计算得到的Au—Au键和 Au—X键振动频率也与实验数据符合较好. 还运用含时密度泛函理论计算了[Au(CH₂)₂PH₂]₂X₂的电子激发能, 对分子在紫外-可见光谱范围内的电子跃迁进行了分析, 考察了卤素配体对激发能的影响, 并结合分子轨道能级的变化对此给予了解释.     

Au(II)化合物[Au(CH2)2PH2]2X2 (X＝F, Cl, Br, I)的量子化学理论研究

采用从头计算HF, MP2方法和密度泛函理论, 对Au(II)系列化合物[Au(CH₂)₂PH₂]₂X₂ (X＝F, Cl, Br, I)的几何结构、电子结构和振动频率进行了研究. 研究表明Au的5d和6s电子参与Au—Au以及Au—X之间的成键. Au—Au, Au—X键强烈的电子相关作用使HF方法不适于该体系的研究, BP86和B3LYP两种泛函给出较大的Au—Au和Au—X键长, 而MP2方法和局域的密度泛函方法则给出了合理的结构参数. 局域密度泛函方法计算得到的Au—Au键和 Au—X键振动频率也与实验数据符合较好. 还运用含时密度泛函理论计算了[Au(CH₂)₂PH₂]₂X₂的电子激发能, 对分子在紫外-可见光谱范围内的电子跃迁进行了分析, 考察了卤素配体对激发能的影响, 并结合分子轨道能级的变化对此给予了解释.     

Substituent effects in second row molecules : Silicon-containing compounds

Substituent interaction energies are calculated by ab initio molecular orbital methods for the two series SiH₂X^- and SiH₃X for the directly bound substituents X = BH₂, CH₃, NH₂, OH, F and the results compared with those for the corresponding first row species. Interactions with the groups NH₂, OH, F are as large in the neutral as in the anionic series and this is attributed to the presence of important π-bonding interactions, supplementing the effects of inductive withdrawal of σ-electrons. The restoration of charge neutrality by π-donation to silicon is more important in the neutral molecules, σ-electron transfer from silicon in the anions. π-Bonding with the π-acceptor substitutent BH₂ is favourable, as it is in the CH₃X and CH₂X^- systems, but with π-donor substituents the interactions are always destabilizing.     

Zur Möglichkeit der planaren Tetrakoordination von Elementen der IV. Hauptgruppe (C,Si, Ge)

On the Possibility of Planar Tetracoordination of the Fourth Main Group Elements (C, Si, Ge) Semiempirical MO calculations (CNDO/2, EHT) have been used to examine the ability of silicon, carbon, and germanium to form planar tetracoordinated compounds. The calculations have been performed for the tetrahedral ground state structures (T_d – symmetry) as well as for the artificial planar structures (D_4h – symmetry) of the compounds CH₄, SiH₄, GeH₄, and CF₄, SiF₄, GeF₄. A comparison between the tetrahedral and planar species showed, that all planar species are less stable. Furthermore they have larger bond distances and their bonds are stronger polarized. The possibility of the examined compounds to form planar structures increases with growing atomic number of the central atom and with increasing electronegativity of the substituents.     

Theoretical Study of Interaction Between S2 and SiHx (x=1, 2, 3) in Porous Silicon

The interaction between S₂ molecule and SiH_x (x=1, 2, 3) in porous silicon is investigated using the B3LYP method of density functional theory with the lanl2dz basis set. The model of porous silicon doped with CH₃,Si-O-Si and OH species is built. By analyzing the binding energy and electronic transfer, we conclude that the interaction of S₂ molecule with SiH_x (x=1, 2, 3) is much stronger than the interaction of S₂ molecule with CH₃ and OH, as S₂ molecule is located in different sites of the model. Using the transition state theory, we study the Si₂H₆+S2→H₃SiH₂SiS+HS reaction, and the reaction energy barrier is 50.2 kJ/mol, which indicates that the reaction is easy to occur.     

Density functional study of XH4 (XSi and Ge) reactivity upon dissociative adsorption onto the Si(100) surface

Total energy calculations based on density functional theory (DFT) with generalized gradient approximation (GGA) and ultrasoft pseudopotential approximation and an analysis tool of atom‐resolved density of states (ADOS) have been used to investigate (1) the energetic profiles for the possible initial dissociative adsorption of XH₄ (X?Si and Ge) onto the Si(100)? (2 × 2) surface to evaluate their reactivity and (2) the effect of surface electronic states of Si(100)? (2 × 2) on gaseous molecular precursors XH₄ (X?Si and Ge) during initial dissociative adsorption to understand the factors governing their reactivity. Our calculated lower‐energy barrier for initial dissociative adsorption of GeH₄ is due to the forming of stronger bond of Si? H between H within GeH₄ and buckled‐down Si atom on the Si(100)? (2 × 2) surface accompanying the larger extent of unbuckling of the buckled Si?Si dimer on the Si(100)? (2 × 2) surface at the transition state. Our evaluated better reactivity for GeH₄ than SiH₄ (a factor of around 14.6) is slightly larger than observed higher reactivity for GeH₄ than SiH₄ (a factor of between 2 and 5 depending on the incident kinetic energy) employed supersonic molecular bean techniques. Finally, our calculated ADOS indicate that the surface electronic states of buckled Si?Si dimer on the Si(100)? (2 × 2) surface energetically favorably participate in the transition state during GeH₄ initial dissociative adsorption to reduce the energy barrier, i.e., enhance its reactivity, in comparison with SiH₄ initial dissociative adsorption onto the Si(100)? (2 × 2) surface under the same reaction conditions. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

硝基芳烃对梨形四膜虫毒性的QSAR研究

用30种硝基芳烃化合物DFT-B3LYP/6-311G**全优化计算结构参数: 最高占有和最低未占分子轨道能级(E_HOMO和E_LUMO)、次最高占有和次最低未占分子轨道能级(E_NHOMO和E_NLUMO)、前线轨道能级差(ΔE＝E_LUMO－E_HOMO)、分子的总能量(E_T)、硝基和硝基碳上净电荷(Q_NO2和Q_C-NO2)、与卤素相连碳原子上的净电荷(Q_C-X)、分子偶极矩(μ)和分子体积(V), 结合文献中的疏水性参数(log K_ow), 按取代基类型和数目分类进行其对梨形四膜虫急性毒性(－log IC₅₀)的定量构效关系(QSARs)研究. 结果表明, 前线轨道能级对硝基芳烃毒性作用有重要贡献, 硝基芳烃对梨形四膜虫的毒性作用主要以与生物分子发生电子转移等化学反应为主, 单硝基芳烃的毒性作用还与疏水性有关. 卤素的存在增加了硝基芳烃化合物的毒性, 卤素易被亲核取代. 对30种标题物作多元线性回归, 所得模型(－log IC₅₀＝18.037＋10.446Q_NO2－41.323ΔE－20.471E_NLUMO＋24.989E_NHOMO, n＝30, R＝0.962, SE＝0.185, F＝78.640, Sig.＝0.000)具有较高毒性预测作用.     

Gas‐phase reactions of XH3+ (X = C,Si, Ge) with NF3: a comparative investigation on the detailed mechanistic aspects

The gas‐phase reaction of CH₃⁺ with NF₃ was investigated by ion trap mass spectrometry (ITMS). The observed products include NF₂⁺ and CH₂F⁺. Under the same experimental conditions, SiH₃⁺ reacts with NF₃ and forms up to six ionic products, namely (in order of decreasing efficiency) NF₂⁺, SiH₂F⁺, SiHF₂⁺, SiF⁺, SiHF⁺, and NHF⁺. The GeH₃⁺ cation is instead totally unreactive toward NF₃. The different reactivity of XH₃⁺ (X = C, Si, Ge) toward NF₃ has been rationalized by ab initio calculations performed at the MP2 and coupled cluster level of theory. In the reaction of both CH₃⁺ and SiH₃⁺, the kinetically relevant intermediate is the fluorine‐coordinated isomer H₃X‐F‐NF₂⁺ (X = C, Si). This species forms from the exoergic attack of XH₃⁺ to one of the F atoms of NF₃ and undergoes dissociation and isomerization processes which eventually result in the experimentally observed products. The nitrogen‐coordinated isomers H₃X‐NF₃⁺ (X = C, Si) were located as minimum‐energy structures but do not play an active role in the reaction mechanism. The inertness of GeH₃⁺ toward NF₃ is also explained by the endoergic character of the dissociation processes involving the H₃Ge‐F‐NF₂⁺ isomer. Copyright © 2009 John Wiley & Sons, Ltd.     

Statistische Modellrechnungen an den Molekülen CH4, SiH4, GeH4, SnH4 und PbH4 nach der Einzentrenmethode

Zusammenfassung Mit einem Einzentren-Ansatz werden Bindungsabstände und Gesamtenergien der Moleküle CH₄, SiH₄, GeH₄, SnH₄ und PbH₄ berechnet. Die statistische Betrachtungsweise der Elektronen nach Gombás und Ladányi [1] wird mit der Edelgas-Modellvorstellung nach Hartmann und Gliemann [2] verknüpft. Die Ergebnisse liegen in guter Übereinstimmung mit den vorliegenden experimentellen Daten. Bindungsabstand und Gesamtenergie des Moleküls PbH₄ werden erstmals berechnet.

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Statistical OCE-calculations on the molecules CH₄, SiH₄, GeH₄, SnH₄ and PbH₄

OCE-calculations are reported for ground state energies and bond distances of the hydrides CH₄, SiH₄, GeH₄, SnH₄ and PbH₄. The statistical atom model (Gombás and Ladányi [1]) is connected with the noble gas model (Hartmann and Gliemann [2]). The results are in good agreement with known experimental values. Bond distance and ground state energy of PbH₄ are presented for the first time.

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Wir danken der DFG für die finanzielle Unterstützung dieser Arbeit.     

Structures and stabilization energies of methyl anions with main group substituents from the first five periods

The effects of substituents (X) on the structures and stabilities of CH₂X^? anions for groups comprised of fourth- and fifth-period main group elements (X = K, CaH, GaH₂, GeH₃, AsH₂, SeH, Br, Rb, SrH, InH₂, SnH₃, SbH₂, TeH, and I) have been investigated by ab initio pseudopotential calculations. Full geometry optimizations have been carried out on the CH₂X^? anions and the corresponding neutral parent molecules, CH₃X, at HF/DZP + and MP2/DZP + levels. Results for substituents from the second (X = Li? F) and third (X = Na? Cl) periods provide comparisons of substituent effects of the main group elements of the first four rows of the periodic table on methyl anions. Frequency calculations characterize the nature of stationary points and show pyramidal CH₂X^? anion structures to be the most stable unless π acceptor interactions (e.g., with BH₂, AlH₂, GaH₂, and InH₂ favor planar geometries. The CH₂X^? stabilization energies [at QCISD(T)/DZP + /MP2/DZP + + ZPE level for X = K? I and QCISD(T)/6?31 + G*/MP2/6?31 + G* + ZPE level] for X = Li? Cl) also show strong π-stabilizing effects for the same substituents. With the exception of CH₃ and NH₂, all substituents stabilize methyl anions, although the σ stabilization by OH and F is small. The SiH₃? PH₂? SH? Cl, GeH₃? AsH₂? SeH? Br, and SnH₃? SbH₂? TeH? I sets of substituents give stabilization energies between 19 and 30 kcal/mol. The stability of methyl anions substituted by the halogens and the chalcogens (X = OH, SH, SeH, and TeH) increases down a group in accord with the increasing substituent polarizability, while for π acceptors (BH₂, AlH₂, GaH₂, and InH₂) the stability decreases down a group in line with their π-accepting ability. © 1994 by John Wiley & Sons, Inc.