Bis（C—p—carboranyl）（C2B10H11）2振动光谱的从头算研究

BiS（C-p-carboranyl）（C2B10H11）2是一种稠合型碳硼烷，由2个C2B10H11集团通过C-C键联结构成．Leites已发表了其实验振动光谱[1]，理论计算尚未见报道，本文对其几何优化、振动光谱及其指认进行从头计算研究．1计算方法首先在STO－3G下对标题化合物D5d与D5h两种构型进行从头算，确定D5d为其稳定构型，进而保持D5d对称性不变，并在6－31G下进行几何优化及振动光谱的理论研究，全部计算采用Gaussion－94程序，在CrayS－MP／11型计算机上完成．2结果与讨论2．1几何优化优化几何及部分实验键长列于表1．标题化合物在D5d与D5h两种…     

Jahn－Teller畸变后D_（2h） C_（60）~－的电子结构和光谱

用ＩＮＤＯ系列方法对Ｃ_（６０）自由基负离子进行了几何构型优化，得到Ｄ_（２ｈ）对称性的构型，表明Ｃ_（６０）~－确实发生了Ｊａｈｎ－Ｔｅｌｌｅｒ畸变，导致单键变短，双键变长，形成１５种键，９种不等同碳原子，其额外负电荷主要分布在赤道附近。以此构型为基础，计算了Ｃ_（６０）~－的电子光谱，与实验值吻合，在对光谱进行理论指认的同时讨论了光谱红移的原因。     

硅硫二元团簇[（SiS2）nSiS]^＋（n=1～3）的结构和稳定性的量子化 …

用密度泛函（ＤＦＴ）方法（Ｂ３ＬＹＰ／６－３１Ｇ＊）研究了硅硫团簇「（ＳｉＳ２）ｎＳｉＳ」＾＋（ｎ＝１～３）的可能几何构型，得到各稳定构型的电子结构，并计算了相应的振动频率，预测了稳定构型的振动光谱，由其稳定构 比较可在理论上预测团簇的生长规律，并可初步预测团簇的形成机理。     

B8N12簇的结构和振动光谱的理论研究

用量子化学从头计算方法研究Ｂ_８Ｎ_（１２）的几何构型、电子结构和振动光谱，讨论其稳定性和化学反应性质。     

硅硫二元团簇（SiS2）n^—（n=1—5）的结构和振动光谱的量子 …

用密度泛函方法研究了硅硫团簇（ＳｉＳ２）＾－ｎ（ｎ＝１－５）的可能几何构型,并计算了相应的振动频率。得到稳定构型的振动光谱。比较其稳定构型可得到团簇的生长规律,由此可初步预测团簇的形成机理。     

The Geometry, Vibrational Frequencies and Thermodynamic Properties of Naphthalene Based on ab initio Calculation

采用ａｂｉｎｉｔｉｏ方法，在ＨＦ／６３１Ｇ水平下计算了萘的几何构型和振动频率．计算所得几何构型和转动惯量与实验结果相符良好．计算所得振动频率平均比实验结果大９．５％左右；经校正（校正系数０．９０５）的计算频率与实验结果很接近．用校正后的频率计算所得不同温度下的热力学性质如标准熵、标准热容等与实验结果相吻合．     

CH_2(~3B_1)自由基与O_2的反应

用时间分辨宫里叶红外发射谱仪（TR-FTIRS），研究了自由基与O2反应的通道及产物的振动态布居．基电子态自由基由351nm紫外激光光解CH2CO生成．观测到振动激发态反应产物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（v2）的相对振动布居，发现v＝4能级的布居数相对于v3　3能级有明显反转．     

尿嘧啶-BH3复合物构型与性质的MP2理论研究

用MP2方法在6—31G基组水平对尿嘧啶-BH3复合物进行了理论计算，以预测该复合物的构型及稳定化能，得到了5种构型，对各构型进行了振动频率分析和自然键轨道分析．结果表明，B与O直接结合的构型比较稳定，其稳定化能分别为95．5和93．4kJ／mol．各种构型都存在不同程度的电荷转移，转移方式和转移量与结合方式有关．复合物的形成使红外光谱中的N-H键，B-H键和C-O键的伸缩振动频率均有所降低．     

硅-硫团(SiS_2)_n~+(n=4,5)的结构和振动光谱的量子化学研究

用密度泛函（ＤＦＴ） 方法研究了硅硫团簇（ＳｉＳ２） ｎ＋（ ｎ ＝ ４ ,５） 的各种可能几何构型和电子结构,并计算了相应的振动光谱,得到了（ＳｉＳ２）ｎ＋ 的形成规律,即（ＳｉＳ２）ｎ ＋ 以硅、硫交错形成四元环链的形式增长．     

AlCn及AlC+n(n=1-4)原子簇的理论研究

用ab initio能量解析梯度法，在UHF（RHF）／3－21G水平上优化得到AlCn，AlCn+（n＝1～3）的四十三个构型，在RHF（UHF）／3－21G水平上优化得到AlC4，AlC4+的二十六个构型，CISD能量．从能量角度所研究的AlCn，AlCn+（n=1～4）构型中，最稳定的构型均是线性构型，且Al全都在端点上，同文献报导的理论和实验结果相一致．此外，还研究了原子簇的离子化能，原子平均结合能以及原子簇的碎片化通道和碎片化能，并计算了上述最稳定构型的谐振动光谱常数．     

α-Amino acid derived enaminones and their application in the synthesis of N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates and other heterocycles

A new and simple synthesis of novel N-protected methyl 5-substituted-4-hydroxypyrrole-3-carboxylates, which exist in equilibrium with their 4-oxo tautomers, has been developed in two steps starting from N-protected α-amino acids. The key intermediates are enaminones, which can also be isolated, characterized, and used for the construction of other functionalized heterocycles, before they spontaneously decompose to pyrrole products. 4-Hydroxypyrroles are prone to partial aerial oxidation but can be efficiently alkylated or reduced to stable polysubstituted pyrrolidine derivatives.     

Specific intramolecular aromatic CH insertion of diazosulfonamides

The chemoselectivity in the intramolecular CH insertion of various diazosulfonamides has been experimentally studied. The results reveal that the aliphatic 1,4-, 1,5-, or 1,6-C(sp³)?H insertions of diazosulfonamides are not accessible, while the aromatic 1,5-C(sp²)?H insertion can be realized specifically by adjusting the diazo-adjacent group. In addition, the general chemoselectivities in the intramolecular CH insertions of diazosulfonyl compounds are summarized. Generally, diazosulfones undergo both aromatic 1,5-C(sp²)?H and aliphatic 1,5- and 1,6-C(sp³)?H insertions, while diazosulfonates undergo aliphatic 1,5- and 1,6-C(sp³)?H insertions. However, diazosulfonamides only undergo aromatic 1,5-C(sp²)?H insertion.     

N-Heterocyclic carbene-palladacyclic complexes: synthesis,characterization and their applications in the C-N coupling and α-arylation of ketones using aryl chlorides

N-Heterocyclic carbene-palladacyclic complexes 3 were successfully achieved in a one-pot procedure under mild conditions. The structure of 3a was unambiguously confirmed by X-ray single crystal diffraction and it was an active catalyst in the Buchwald-Hartwig amination and α-arylation of ketones even at very low catalyst loadings (0.01?mol%).     

Iodine-mediated oxidative Pictet-Spengler reaction using terminal alkyne as the 2-oxoaldehyde surrogate for the synthesis of 1-aroyl-β-carbolines and fused-nitrogen heterocycles

An efficient iodine-mediated oxidative Pictet-Spengler reaction in dimethyl sulphoxide (DMSO) using terminal alkynes as the 2-oxoaldehyde surrogate for the synthesis of aryl (9H-pyrido[3,4-b]indol-1-yl)methanones is described. The scope of the protocol includes the total synthesis of Fascaplysin, Eudistomins Y₁ and Y₂. The methodology is extended for preparing pyrrolo[1,2-a]-quinoxaline and indolo[1,5-a]quinoxaline derivatives. The utility of 1-aroyl-β-carbolines was demonstrated by performing palladium-catalyzed β-carboline directed ortho-C(sp2)-H functionalization of the phenyl ring with thiomethyl (SMe) group using DMSO as source and for accessing 4-aryl-canthin-6-ones.     

Facile synthesis of bicyclic 1-arylpyrazol-5-ones

In this Letter, we described a facile method for constructing fused bicyclic 1-arylpyrazol-5-one ring system. We employed various methylene-containing carboxylic acids as the substrates and proved that the pyrazolone ring closure requires activated methylene group in intermediate II. Accordingly, a series of structurally diversified, fused bicyclic 1-arylpyrazol-5-ones was prepared in moderate to high yields using the requisite substrates.     

A carbanion induced synthesis of highly congested pyrazole and imidazole containing heterocycles

An efficient approach to the synthesis of highly congested di, penta and hexacyclic pyrazoles as well as imidazole fragment containing novel heterocyclic molecule has been developed through a carbanion induced transformation of suitably functionalized 2H-pyran-2-ones, benzo[h]chromene and thiochromeno[4,3-b]pyrans. Due to the presence of fluorescence, we report their prime application metal sensor as off/on switching in ferric ions.     

Synthesis of pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles by Curtius reaction in Morita-Baylis-Hillman derivatives

Synthesis of substituted pyrrolo[1,2-a]pyrazines and pyrazino[1,2-a]indoles from the Morita-Baylis-Hillman derivatives of acrylates via saponification followed by Curtius reaction is described.     

正丁胺对激光染料荧光谱影响的研究

用正丁胺作为碳源,采用射频辉光放电制备碳膜,选用激光染料R6G和聚乙二醇混合液作为蒸气源,采用单源热蒸发,在蒸发室与染料同时沉积得到混合膜,用拉曼光谱和红外光谱分析了碳膜的结构和键合方式,分析表明:碳膜中存在胺基团和氢原子.混合膜的荧光谱测量结果表明,认为正丁胺对染料荧光谱的影响是因为胺基和氢原子的存在.     

Selective synthesis of 4,5-dihydroimidazo- and imidazo[1,5-a]quinoxalines via modified Pictet–Spengler reaction

An efficient tandem approach for the selective synthesis of 4,5-dihydroimidazo[1,5-a]quinoxalines 6a–g and imidazo[1,5-a]quinoxalines 7a–h by the reaction of 2-imidazolyl anilines 4a–c with aryl aldehydes 5a–k under mild reaction conditions is described. Introduction of electron releasing alkyl groups in substrates 4a–b was found to be instrumental for the success of the reaction.     

Understanding the Diels-Alder reactivity of 1,2-azaborine analogues

The Diels-Alder reactivity of 1,2-heteroborines (H₄C₄B(H)X, X?=?NH, PH, AsH; O, S, Se) has been computationally explored by means of Density Functional Theory (DFT) calculations. The influence of the HB?=?X fragment on the reactivity of the system has been quantitatively analyzed in detail by means of the so-called Activation Strain Model (ASM) of reactivity. It is found that the interaction between these species and the dienophile is significantly stronger than that computed for their all-carbon isoelectronic counterpart, benzene. In addition, the strain energy plays a key role in the observed reactivity trends. The role of the aromaticity strength of these heteroarenes on the reactivity is also assessed.