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采用量子化学密度泛函理论(DFT) B3LYP/6-31G(d)方法对14顶点双取代碳硼烷和金属硼烷几何构型进行优化, 结合有限场(FF)方法计算了各体系的极化率和二阶超极化率. 同时金属硼烷中金属原子采用赝势基组进行计算, 讨论基组对计算结果的影响. 结果表明, 14顶点碳硼烷和金属硼烷中碳和金属元素的成键方式不同, 金属硼烷中各原子间距离比碳硼烷中大, 平面偏移角增大. 金属原子的引入有效增加分子的NLO系数, 同时金属硼烷的前线分子轨道能级差比碳硼烷小很多, 金属硼烷材料有可能表现出半导体甚至导体特性, 金属原子采用不同基组对计算结果影响不大. 相似文献
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Wade规则在稠合型硼烷等中的应用 总被引:6,自引:0,他引:6
本文把Wade规则推广应用于稠合型硼烷和稠合型金属碳硼烷中,导出计算它们价电子数(NVE)的公式。对于稠合型硼烷,本文公式与唐敖庆等的拓扑结构规则的计算结果相同。但本文公式的适用范围比上述两个规则广。 相似文献
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碳硼烷结构规则的量子化学计算 总被引:1,自引:0,他引:1
本文对一系列封闭型CnB5-n(n=0~5)和CnB6-n(n=0~6)碳硼烷骨架及巢型C4B5-n(n=0~5)碳硼烷骨架进行了EHMO量子化学计算,根据计算结果讨论了碳硼烷的结构规则. 相似文献
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本文报道(N,N-二烃基胺基)二氯硼烷的反常三烃化反应, 2-苯并噻唑基Grignard剂与(N,N-二乙胺基)二氯硼烷反应, 得到二乙胺合三(2-苯并噻唑基)硼烷, 并讨论了反应机理。分子结构经X单晶结构分析确证。晶体结构属正交晶系, 空间群为P212121, 晶胞参数a=11.570(3), b=12.496(4), c=16.577(4)nm; Z=4, V=2397.3nm^3,Dc=1.348g/cm^3, μ(MoKa)=3.167cm^-^1。 相似文献
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用MP2方法和B3LYP方法,在6-31G(d,p)基组下对复合物环硼氮烷-HCl体系和环硼氮烷-CHCl3体系进行优化,研究了其分子间氢键的本质.计算结果表明,氯仿与环硼氮烷分子之间的相互作用使C-H键长缩短,振动频率增大(蓝移),而HCl与环硼氮烷分子之间的相互作用使H-Cl键长增长,振动频率减小(红移).自然键轨道(NBO)分析表明,影响氢键红移和蓝移主要有3个因素:n(Y)→σ*(X-H)超共轭作用、X-H键轨道再杂化和质子供体电子密度重排.其中,超共轭作用属于键伸长效应,电子密度重排和轨道再杂化属于键收缩效应.环硼氮烷-HCl体系的构型1和2伸长效应处于优势地位导致形成红移氢键;环硼氮烷-CHCl3体系中,由于键收缩效应处于优势地位导致形成蓝移氢键. 相似文献
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本文报道(N,N-二烃基胺基)二氯硼烷的反常三烃化反应。2-苯并噻唑基Grignard剂与(N,N-二乙胺基)二氯硼烷反应,得到二乙胺合三(2-苯并嚷唑基)硼烷,并讨论了反应机理。分子结构经X单晶结构分析确证。晶体结构属正交晶系,空间群为P2_12_12_1,晶胞参数a=11.570(3),b=12.496(4),c=16.577(4)nm;Z=4,V=2397.3nm~3,D_0=1.348g/cm~3,μ(MoK_a)=3.167cm~(-1)。 相似文献
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在路易斯酸催化下,碳硼烷分别与对氰基溴化苄、三苯基膦在甲苯溶液里回流,前者反应中,制备得碳硼烷的硼端与对氰基苄基中的亚甲基直接偶联的产物1,通过调整催化剂的含量,可以显著地提高含B-Cl键的产物2的产率;与三苯基膦的反应中,碳硼烷失去一个硼顶,并与三苯基膦中的P原子直接偶联,生成含B-P键的巢式碳硼烷衍生物3。对此两类化合物进行了核磁、质谱、红外及单晶衍射等表征。化合物1和2中均发现碳硼烷的CH与N形成CH…N氢键和CH…π的弱作用,其中化合物2中,还存在CH…Cl。在巢式化合物3中,发现碳硼烷的CH参与了罕见的CH…HC相互作用。这类反应成功合成了含有B-C、B-Cl、B-P键的碳硼烷衍生物。 相似文献
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用MP2/6-31G方法, 对三角锥型分子B3H6X(X=B^2^-, C^-,N, O^+, BH^-, CH和NH^+)及其碎片B3H6和X的结构进行了abinitio研究。结果表明, 当X=NH^+, O^+和N时, B3H6基环上的端氢(Ht)朝着帽基X方向, 而当X=CH, BH^-, B^2^-和C^-时, Ht却转向帽基X的方向。这种特征可用配位原子的电负性和配位原子轨道的弥散性给以说明。我们还进一步研究了B3H6X系列化合物的结合能和稳定性。 相似文献
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Shore SG Hamilton EJ Bridges AN Bausch J Krause-Bauer JA Dou D Liu J Liu S Du B Hall H Meyers EA Vermillion KE 《Inorganic chemistry》2003,42(4):1175-1186
The structure of [PPh(3)(benzyl)][B(10)H(11)] was determined at -123 degrees C and 24 degrees C by single-crystal X-ray analyses. The B(10) core of [B(10)H(11)](-) is similar in shape to that of [B(10)H(10)](2)(-). The 11th H atom asymmetrically caps a polar face of the cluster and shows no tendency for disorder in the solid state. Variable temperature multinuclear NMR studies shed light on the dynamic nature of [B(10)H(11)](-) in solution. In addition to the fluxionality of the cluster H atoms, the boron cage is fluxional at moderate temperatures, in contrast to [B(10)H(10)](2)(-). Multiple exchange processes are believed to take place as a function of temperature. Results of ab initio calculations are presented. Crystal data: [PPh(3)(benzyl)][B(10)H(11)] at -123 degrees C, P2(1)/c, a = 9.988(2) A, b = 18.860(2) A, c = 15.072(2) A, beta = 107.916(8) degrees, V = 2701.5(7) A(3), Z = 4; [PPh(3)(benzyl)][B(10)H(11)] at 24 degrees C, P2(1)/c, a = 10.067(5) A, b = 19.009(9) A, c = 15.247(7) A, beta = 107.952(9) degrees, V = 2775(2) A(3), Z = 4. 相似文献
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Wei L Yang B Yang R Huang C Wang J Shan X Sheng L Zhang Y Qi F Lam CS Li WK 《The journal of physical chemistry. A》2005,109(19):4231-4241
The photoionization and dissociative photoionization of acetone have been studied at the photon energy range of 8-20 eV. Photoionization efficiency spectra for ions CH3COCH3+, CH3+, C2H3+, C3H3+, C3H5+, CH(2-)CO+, CH3CO+, C3H4O+, and CH3COCH2+ have been measured. In addition, the energetics of the dissociative photoionization has been examined by ab initio Gaussian-3 (G3) calculations. The computational results are useful in establishing the dissociation channels near the ionization thresholds. With the help of G3 results, the dissociation channels for the formation of the fragment ions CH3CO+, CH2CO+, CH3+, C3H3+, and CH3COCH2+ have been established. The G3 results are in fair to excellent agreement with the experimental data. 相似文献
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Recent spectroscopic advances have led to the first determinations of infrared vibration-rotation bands of polyatomic molecular ions. These initial detections were guided by ab initio predictions of the vibrational frequencies. The calculations reported here predict the vibrational frequencies of additional ions which are candidates for laboratory analysis. Vibrational frequencies of neutral molecules computed at three levels of theory, HF/3-21G, HF/6-31G*, and MP2/6-31G*, were compared with experiment and the effect of scaling was investigated to determine how accurately vibrational frequencies could be predicted. For 92% of the frequencies examined, uniformly scaled HF/6-31G* vibrational frequencies were within 100 cm-1 of experiment with a mean absolute error of 49 cm-1. This relatively simple theory thus seems suitable for predicting vibrational frequencies to guide laboratory spectroscopic searches for ions in the infrared. Hence, the frequencies of 30 molecular ions, many with astrochemical significance,were computed. They are CH2+, CH3+, CH5+, NH2+, NH4+, H3O+, H2F+, SiH2+, PH4+, H3S+, H2Cl+, C2H+, classical C2H3+, nonclassical C2H3+, nonclassical C2H5+, HCNH+, H2CNH2+, H3CNH3+, HCO+, HOC+, H2CO+, H2COH+, H3COH2+, H3CFH+, HN2+, HO2+, C3H+, HOCO+, HCS+, and HSiO+. 相似文献
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Tulub AA 《The Journal of chemical physics》2004,120(3):1217-1222
DFT:B3LYP ab initio molecular dynamics (MD) approach is used to elucidate the properties of the Zundel and Eigen, H5O2+ and H9O4+, proton complexes in the triplet state. The simulation considers the complexes in the gas phase (isolated complexes) and inside the clusters composed of 32, 64, and 128 water molecules, mimicking the behavior of aqueous solutions. MD simulations reveal three distinct periods. For the complex in solutions, the periods are smoothed out. The H5O2+ and H9O4+ complexes in the triplet state undergo structural rearrangements, which eventually result in hydrogen elimination. For the H5O2+, the hydrogen is eliminated from the center of the water cluster, whereas for the H9O4+ it is removed from a near-surface water molecule. The rate of hydrogen elimination decreases with increasing the number of water molecules surrounding the complex. 相似文献
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Huang YX Hochrein O Zahn D Prots Y Borrmann H Kniep R 《Chemistry (Weinheim an der Bergstrasse, Germany)》2007,13(6):1737-1745
The templated microporous compounds [H2(Templ.)][MnII{B2P3O12(OH)}], [templates: 1,3-diaminopropane, C3H10N2 (DAP); piperazine, C4H10N2 (PIP); 1,4-diazacyclo[2.2.2]octane, C6H12N2 (DABCO)] were prepared under mild hydrothermal conditions. The crystal structures (H2DAP-Mn: Pmc2(1) (no. 26), a=1259.43(5), b=949.86(5), c=1135.92(5) pm, Z=4; H2PIP-Mn: Ima2 (no. 46), a=1257.9(1), b=948.69(8), c=1158.19(8) pm, Z=4; H2DABCO-H2PIP-Mn: Ima2 (no. 46), a=1262.90(7), b=961.05(5), c=1151.42(7) pm, Z=4) are characterized by identical framework connectivities [MnII{B2P3O12(OH)}]2-, but vary in shapes (diameters) of the structural channels depending on the shapes of the templating molecule ions. The situation clearly reflects the directing effect of true templates during endotemplating reactions. The experimental results (preparation, chemical analyses, and X-ray refinements) are supported by detailed ab initio calculations (structure optimizations). 相似文献
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The structures of 8-G-1-(p-YC(6)H(4)Se)C(10)H(6) (1 (G = Cl) and 2 (G = Br): Y = H (a), OMe (b), Me (c), Cl (d), Br (e), COOEt (f), and NO(2) (g)) were investigated by X-ray crystallographic analysis, NMR spectroscopy, and ab initio MO calculations. The structures of all members in 1 and 2 are concluded to be type B, which is in striking contrast to the type A structure for 4d-g (4 (g(n)), where G = H). The Se-C(i) bond of the p-YC(6)H(4)Se group in 8-G-1-(p-YC(6)H(4)Se)C(10)H(6) is almost perpendicular to the naphthyl plane in type A, and it is located on the plane in type B. The chlorine and bromine substitution at the 8-position in 1 and 2 dramatically changes the type A structure of 4 (g(n)) to type B. The nonbonded G- - -Se-C 3c-4e type interaction must contribute to stabilize the type B structure. The type B structure in 1 and 2 should also be more stabilized than the same structure in 4 by the 3c-4e type interaction: The structure of 4b is type B in the crystals and type B would be more stable for 4c and might be for 4a in solutions. Ab initio MO calculations are performed on 8-G-1-(p-YC(6)H(4)Se)C(10)H(6), 8-G-C(10)H(6)SeH-1, and models HG- - -SeH(2), where G = Cl, Br, and F, to clarify the reason for the dramatic change in the structures. The type B structure is optimized to be more stable than the type A for all species examined, which supports the observations. The energy differences between type B and type A are larger for the models than for the naphthalenes. While the superiority of the type B for the former is Br > Cl > F, that of the latter is Br approximately Cl >/= F. These results show that the main factor of the structural change from type A to type B is the nonbonded G- - -Se-C 3c-4e interaction. The electronic effect of halogens through the naphthalene pi-framework would also contribute to some extent, although the direct comparison of the evaluated values between the naphthalene systems and the models is not so easy. Factors to stabilize the two structures of 1, 2, 4, and 8-(MeSe)-1-(p-YC(6)H(4)Se)C(10)H(6) are reexamined from a viewpoint of the nonbonded G- - -Se-C 3c-4e interaction (G dependence), together with the electronic effect of Y (Y dependence). 相似文献
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QuantumChemistryStudyontheGeometricalStructuresofSmallCentipedo-boranes¥ZhongShi-Jun;WangYin-Gui;ZhangQian-Er(StateKeyLaborat... 相似文献
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Alexandrova AN Birch KA Boldyrev AI 《Journal of the American Chemical Society》2003,125(36):10786-10787
The structural chemistry of boron is dominated by 3D structures (polyhedra), while in carbon structural chemistry the planar aromatic structures are more abundant. In this Communication we present results of ab initio calculations showing that the polyhedral boranes can be flattened into planar aromatic structures similar to their carbon analogues. We predicted that a B6H62- octahedron (in Li2B6H6), a B5H52- trigonal bipyramid (in Li2B5H5), a B7H72- pentagonal bipyramid (in Li2B7H7), and a B10H84- bioctahedron with a joint edge (in Li4B10H8) can be reduced to a planar aromatic B6H66- hexagon (in Li6B6H6), to a planar pentagon B5H56- (in Li6B5H5), to a planar heptagon B7H76- (in Li6B7H7), and to a naphthalene-like B10H810- (in Li10B10H8). Ab initio prediction of these new planar aromatic boranes shows that a large new family of planar aromatic all-boron molecules is possible. 相似文献