C64H6的结构和光谱的理论研究

本文用INDO系列方法研究了C64H6的结构与光谱, 表明C64H6有C2v和Cs两种稳定构型, 其中C2v构型能量较低, 讨论其加成及环加成产物对称性的规律并与13C NMR谱的实验结果相结合。计算了两种构型的电子光谱, 对电子跃迁进行了理论指认,并讨论了C64H6谱带红移的原因, 理论计算结果与实验事实基本吻合。     

Ti8C12H8簇的理论研究

用量子化学从头计算方法, 预测了Ti8C12H8簇的几何结构、电子结构, 分析讨论了该簇的成键和化学反应性质。     

碳笼烯C32和碳笼烷C32H32的量子化学研究

用量子化学计算方法ＭＮＤＯ和ＡＭ１研究了具有Ｏｈ对称性的碳笼烯Ｃ３２和碳笼烷Ｃ３２Ｈ３２的几何结构和电子结构及其稳定性，ＡＭ１水平下，评论Ｃ３２的基态性质和分子振动。     

C28H4-nCln(n=1~3)与CH4-nCln(n=1~3)的结构和电子光谱的理论研究

用INDO系列方法对C28H3Cl, C28H2Cl2, C28HCl3, CH3Cl, CH2Cl2, CHCl3进行了几何构型优化, C28H3Cl, C28HCl3, CH3Cl, CH3Cl为C3v对称性,C28H2Cl2, CH2Cl2为C2v对称性, 这六个分子的基态都是稳定闭壳层分子, 以此构型为基础计算了上述分子的电子光谱, C28H4-nCln(n=1~3)的电子光谱属于理论预测性质。     

C6H5—H…X分子间氢键的理论计算

利用密度泛函理论B3LYP方法, 在6-311+G(3df,2p)水平上对C6H5—H…X型分子间氢键进行了几何构型优化、氢键相互作用能、电子密度分布等计算. 其中C6H6为质子供体, HCOH、H2O、NH3、CH2NH和HCN为质子受体. 从电荷布居分析、自然键轨道等角度详细地讨论了C6H5—H…X 体系中, 共轭π键、O和N的不同键型结构对氢键形成的影响以及孤电子对与C—H 反键轨道之间的相互作用(n→σ*)等.     

混合簇合物(C5H5FeC5H4C2Ph)Co2(CO)6的结构研究

本文用电化学方法和X射线单晶结构分析, 研究了混合簇合物(C5H5FeC5H4C2Ph)Co2(CO)6的结构, 由循环伏安结果, 分别讨论了簇合物中(C5H5FeC5H4和C2O2中心的成键性质, X射线单晶结构分析表明: 晶体属单斜晶系, 空间群为P21, 晶胞参数a=11.845(6), b=8.155(6), c=24.031(6)A, β=90.88°,晶胞中分子数Z=4, 密度Do=1.637g.cm^-^2, 分析了(C5H5FeC5H4C2Ph)Co2(CO)6的结构特点, 并从成键角度讨论了(RC2R^1)Co(CO)6类簇合物的结构随RC2R^1不同而变化的规律。     

混合簇合物(C5H5FeC5H4C2Ph)Co2(CO)6的结构研究

本文用电化学方法和X射线单晶结构分析, 研究了混合簇合物(C5H5FeC5H4C2Ph)Co2(CO)6的结构, 由循环伏安结果, 分别讨论了簇合物中(C5H5FeC5H4和C2O2中心的成键性质, X射线单晶结构分析表明: 晶体属单斜晶系, 空间群为P21, 晶胞参数a=11.845(6), b=8.155(6), c=24.031(6)A, β=90.88°,晶胞中分子数Z=4, 密度Do=1.637g.cm^-^2, 分析了(C5H5FeC5H4C2Ph)Co2(CO)6的结构特点, 并从成键角度讨论了(RC2R^1)Co(CO)6类簇合物的结构随RC2R^1不同而变化的规律。     

C120异构富勒烯分子的AM1半经验量子化学研究

以哑铃状2C60聚合体、花生壳状2C60聚合体以及C120富勒烯分子为研究对象,采用AM1半经验量子化学方法,计算了3种C120异构富勒烯分子的几何构型、电子结构、分子能量、疏水常数、极化率与偶极矩;然后,根据计算结果,分析对比了3种C120异构体分子的化学稳定性与物理化学特性.研究结果表明,3种C120分子的形成均为吸热反应,它们的稳定性排序为:C120富勒烯>花生壳状2C60>哑铃状2C60分子.     

C36衍生物C36H12和C36X12簇分子的理论研究

采用从虎ＨＦ／ＳＴＯ－３Ｇ方法,对３６及其衍生物Ｃ３６Ｈ１２和Ｃ３６Ｘ１２（Ｘ＝Ｆ,Ｃｌ,Ｂｒ,Ｉ）进行计算研究,讨论了Ｃ３６Ｈ１２和Ｃ３６Ｘ１２簇分子几何结构随卤素Ｘ原子序数变化的规律,分子的稳定性及电荷转移情况,结果表明,Ｃ３６Ｈ１２和Ｃ３６Ｆ１２在所有簇分子中是较为稳定的。     

不饱和类碳烯H2C(=)CLiBr的DFT研究

采用量子化学计算方法，在B3LYP／6－311G^*水平上全优化得到了不饱和类碳烯H2C＝CLiBr的平衡结构，结果表明，不饱和类碳烯H2C＝CLiBr只有两种平衡结构，对这两种平衡结构之间相互转化的过渡态进行计算，求得了转化势垒，根据计算得到的微观性质，采用统计热力学方法，研究了两种平衡结构之间相互转化的热力学性质，进而讨论了两种平衡结构在不同温度下的稳定性问题，在计算得到振动频率及强度的基础上，模拟了稳定平衡结构的红外光谱图。     

Role of encapsulation of Na+ and F- ions on the Diels-Alder reactivity of C32

The density functional theory (DFT)-based Becke's three parameter hybrid exchange functional and Lee-Yang-Parr correlation functional (B3LYP) calculations have been performed to understand the role of encapsulation of Na(+) and F(-) ions on the Diels-Alder reactivity of C(32). In this context, C(32) has been taken as the dienophile and cis-1,3-butadiene has been considered as diene. Results obtained from the calculations on the Na(+)@C(32) and F(-)@C(32) have also been compared with that of C(32). It is found from the results that encapsulated Na(+) ion acts as a catalyst, whereas the encapsulated F(-) does not accelerate the reaction between C(32) and cis-1,3-butadiene. Thus, the reactivity of F(-)@C(32) is less than that of free C(32) and Na(+)@C(32). Formation of adduct involving [5,5]-B bond is preferred over other bonds. The energy decomposition analysis has been applied to understand the role of confinement on an encaged ion. The part played by the charge transfer interaction is evident from the NBO analysis. The frontier orbital analysis points out that the reaction is driven by the normal electron demand.     

Rotational spectrum and carbon-13 hyperfine structure of the C3H, C5H, C6H, and C7H radicals

By means of Fourier transform microwave spectroscopy of a supersonic molecular beam, we have detected the singly substituted carbon-13 isotopic species of C(5)H, C(6)H, and C(7)H. Hyperfine structure in the rotational transitions of the lowest-energy fine structure component ((2)Pi(12) for C(5)H and C(7)H, and (2)Pi(32) for C(6)H) of each species was measured between 6 and 22 GHz, and precise rotational, centrifugal distortion, Lambda-doubling, and (13)C hyperfine coupling constants were determined. In addition, resolved hyperfine structure in the lowest rotational transition (J = 32-->12) of the three (13)C isotopic species of C(3)H was measured by the same technique. By combining the centimeter-wave measurements here with previous millimeter-wave data, a complete set of (13)C hyperfine coupling constants were derived to high precision for each isotopic species. Experimental structures (r(0)) have been determined for C(5)H and the two longer carbon-chain radicals, and these are found to be in good agreement with the predictions of high-level coupled-cluster calculations. C(3)H, C(5)H, and C(7)H exhibit a clear alternation in the magnitude and sign of the (13)C hyperfine coupling constants along the carbon-chain backbone. Because the electron spin density is nominally zero at the central carbon atom of C(3)H, C(5)H, and C(7)H, and at alternating sets of carbon atoms of C(5)H and C(7)H, owing to spin polarization, almost all of the (13)C coupling constants at these atoms are small in magnitude and negative in sign. Spin-polarization effects are known to be important for the Fermi-contact (b(F)) term, but prior to the work here they have generally been neglected for the hyperfine terms a, c, and d.     

First-principles study of interaction of cluster Au32 with CO, H2, and O2

First-principles calculations are performed to study the interaction of cluster Au(32) with small molecules, such as CO, H(2), and O(2). The cagelike Au(32)(I(h)) shows a higher chemical inertness than the amorphous Au(32)(C(1)) with respect to the interaction with small molecules CO, H(2), and O(2). H(2) can only be physically adsorbed on Au(32)(I(h)), while it can be dissociatively chemisorbed on Au(32)(C(1)). Although CO can be chemically adsorbed on Au(32)(I(h)) and Au(32)(C(1)) with one electron transferred from Au(32) to the antibonding pi* orbit of CO, it is bound more strongly on Au(32)(C(1)) than on Au(32)(I(h)). Spin polarized and spin nonpolarized calculations result almost identical ground state structures of Au(32)(I(h))-O(2) and Au(32)(C(1))-O(2), in which O(2) is dissociatively chemisorbed.     

X-ray crystallographic proof of the isomer D2-C84(5) as trifluoromethylated and chlorinated derivatives, C84(CF3)16, C84Cl20, and C84Cl32

Minor isomer comes forward: Minor isomer C(84)(5) has been captured by high temperature trifluoromethylation with CF(3)I and chlorination with VCl(4). The compounds C(84)(CF(3))(16), C(84)Cl(20), and C(84)(5)Cl(32) were investigated by X-ray crystallography providing the first direct proof of the cage connectivity of D(2)-C(84)(5). The D(2)-C(84)(5)Cl(32) molecule (see figure; C grey, Cl green) contains two flattened, pyrene-like substructures on opposite poles of the cage resulting in its drum-like shape.     

A catalytic enantioselective hetero Diels-Alder approach to the C20-C32 segment of the phorboxazoles

[reaction: see text] An efficient synthesis of the C20-C32 segment of the phorboxazoles has been achieved using an enantioselective hetero Diels-Alder reaction catalyzed by Jacobsen's Cr(III) amino indanol Schiff base catalyst.     

Quantum chemistry study on B32 and B32H2–32

The structures of B32 and B₃₂H^2–₃₂ with I_h symmetry have been investigated by means of ab initio calculations at STO-3G level. The relationship between molecular orbitals of them has been analyzed and their bonding properties have been discussed. Then the possibility of their existence, as well as the similarity and difference between B₃₂ (B₃₂H^2–₃₂) and C₆₀ (C₆₀H₆₀) have been inferred.     

Theoretical Studies on Structures and Properties of Endohedral Fullerenes Complexes： XHn@C32（X=F,O, N,C; n=l-4）

Theoretical studies on structures and properties of endohedral fullerene complexes formed by encapsulating small molecules of HF, H20, NH3, and CH4 in a C32 fullerene cage, were carried out by ab initio method. Current calculations reveal that these processes to encase them in fullerene are energetically unfavorable because of the small cavity size of C32. The red shift in the F-H stretching frequency indicates the potential existence of hydrogen bonding between the HF molecule and the carbon cage.     

Role of four-membered rings in C32 fullerene stability and mechanisms of generalized Stone-Wales transformation: a density functional theory investigation

Density functional theory (DFT) methods have been applied to study C(32) fullerenes built from four-, five-, and six-membered rings. The relative energies of pure C(32) fullerenes have been evaluated to locate three most stable structures, 32:D(4d) with two squares, 1:D(3) without square and 5:C(s) with one square. Structural analysis reveals that there is a rearrangement pathway between the lowest energy classical isomer 1:D(3) and the lowest energy non-classical isomer 32:D(4d), and 5:C(s) behaves just as an intermediate between them. The kinetic processes of generalized Stone-Wales transformation (GSWT) with four-membered rings have been explored and two distinct reaction mechanisms are determined by all the transition states and intrinsic reaction coordinates with PBE1PBE/6-31G(d) approach for the first time. One mechanism is the concerted reaction with a rotating dimer closed to the cage surface and another is the stepwise reaction with a carbene-like sp(3) structure, whereas the latter is sorted into two paths based on four-membered ring vanishing before or after the formation of the carbene-like structure. It is indicated that there is no absolute preference for any mechanism, which depends on the adaptability of different reactants on the diverse mechanisms. Furthermore, it's found that the interconversion process with the participation of squares is more reactive than the rearrangement between C(60)_I(h) and C(60)_C(2v), implying some potential importance of non-classical small fullerenes in the fullerene isomerization.     

Synthesis of the C23-C32 fragment of spirangien

The synthesis of the C23-C32 fragment of spirangien A is reported using Evans’ alkylation, Evans-Metternich aldol reaction and a substrate controlled stereoselective reduction.     

Synthesis and Crystal Structure of CoCl（ieaa）（C10H7—ieai）（C10H7NH2）

1 INTRODUCTION A number of isonitroso-b-diketones and isonitroso-b-ketoesters such as isonitrosoacetyl- acetone(Hiaa), isonitrosobenzoylacetone(Hiba) and isonitrosoethylacetoacetate (Hieaa) have been employed as reagents in spectrophotometric determination of iron, palladium and ruthenium[1]. Transition metal complexes of such ligands[2] are potential models for metal binding sites in ferroverdin[3]. They were found as dyes and light-absorbing agents for the acceleration of the sol…