取代苯酚中共振增强的分子内氢键

根据晶体结构资料，计算了59个邻位取代苯酚中分子内氢键的几何．在STO－3G水平上计算了一些分子中原子部分电荷．结果表明，酚基氧与苯环上碳之间的键长，酚基上氢原子的部分电荷，酚基所在位置处的苯环环内角与取代苯酚的酸常数pKa均有近似线性关系，当邻位上存在硝基或羰基时，内氢键由于共振而得到显著的增强，据此可说明这一类酚的显著酸性     

一种新型双缩合螺吡喃的合成、表征及晶体结构

以过量吲哚啉和5-硝基水杨醛为原料合成了4-(2-亚甲基-1-乙基-3,3-二甲基吲哚啉-2'-基)-6-硝基-1'-乙基-3',3'-二甲基-螺[3,4-二氢-2H-l-苯并吡喃-2,2'-吲哚啉],通过核磁共振、红外光谱、元素分析对其结构进行了表征.同时利用X单晶衍射仪测定了该化合物的结构,结果表明:晶体属单斜晶系,空间群P21/n,a=1.2476(3)nm,b=1.1939(2)nm,c=2.0317(4)nm,α=90°,β=107.45(3)°,γ=90°,Dc=1.205g/cm3,μ=0.077mm-1,F(000)=1120,V=2.8871(10)nm3,Z=4.     

Molecular and Crystal Structure of 1-(4-Chlorophenyl)- 3- (4-Nitrophenyl)- 1-Triazene

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Crystal and Molecular Structure of 4-Hydroxy-3-Methoxy-4-N-Methylstilbazonium Iodide C15H16NO2+·I-

The crystal structure of the title compound C15H16NO2+ · I-(Mr=369. 19) has been determined by single crystal X-ray diffraction analysis. The crystal belongs to tbe monoclinic system with space group P21/c, a=8. 957(1), b=21. 8117(2), c=7. 8760(10)A , β=103.94(1)°, V=1493.8(3)A3, Z=4, Dc=1. 642g cm3,μ=2. 141mm-1, F(000)=728, final R=0. 0264, and Rw=0. 0644(I＞2σ(I)) for 2938 independent reflections. The results show that in the crystal structure of the title compound the planar cations have two configurations, and these cations are anti-parallelly packed through the strong π…π interaction.     

纳米二氧化铈的高压拉曼光谱研究

本文利用金刚石对顶砧高压技术,在0.1MPa～47.5GPa压力范围内对粒径为8nm的纳米CeO2进行了高压拉曼光谱研究。研究结果表明,常压下萤石结构的纳米CeO2(空间群Fm3m)在24.3GPa时开始发生萤石结构到PbCl2类型(空间群Pnam)的结构相变。这个相变为可逆相变,卸压至零压时样品恢复至萤石结构。     

Molecular and Crystal Structure of 1-(4-Chlorophenyl)-3-(2-nitrophenyl)-1-triazene

1　ＩＮＴＲＯＤＵＣＴＩＯＮＩｔｈａｓｂｅｅｎｒｅｐｏｒｔｅｄｔｈａｔ1,3ｄｉｐｈｅｎｙｌｔｒｉａｚｅｎｅｓｈｏｗｓａｎｔｉｔｕｍｏｕｒａｃｔｉｖｉｔｙｃｏｍｐａｒａｂｌｅｔｏｔｈａｔｏｆ3,3ｄｉｍｅｔｈｙｌ1ａｒｙｌｔｒｉａｚｅｎｅｓ.1,3Ｄｉａｒｙｌｔｒｉａｚｅｎｅｓｃａｎａｃｔａｓｐｒｏｄｒｕｇｓ,ｏｒ‘ｃａｒｒｉｅｒｓ’ｏｆｄｉａｚｏｎｉｕｍｃｏｍｐｏｕｎｄｓ,ｓｉｎｃｅｔｈｅｙｕｎｄｅｒｇｏｈｙｄｒｏｌｙｓｉｓｔｏｆｏｒｍａｒｙｌｄｉａｚｏｎｉｕｍｃｏｍｐｏｕｎｄｓ[1,2].Ａｎｄｓｏｍｅｏｎｅｈ…     

C-H…O Hydrogen Bonds and π…π Interaction and the Crystal and Molecular Structures of 3-Nitro-benzylideneaniline-methyl-2’

The title compound (C14H12N2O2,Mr=240.26) crystallizes in the monoclinic system,space group P21/a with a=7.394(1),b=21.334(3),c=7.423(1)A,β=89.82(1)A°,V=1170.8(3)A3,Z=4,Dc=1.363 g/cm3,μ(MoKα)=0.93 cm-1 and F(000)=504.00.The final R and wR are 0.0440 and 0.1370 for 2153 observed reflections (I>2σ(I)),respectively.The dihedral angle between the two phenyl rings is 52.9°and that between the NO2 group and its attached ring is 3.0°.In the crystal,molecules are stacked along [100] throughπ…πinteractions.The C-H…O hydrogen bond (3.403 A,120.4°) laterally connects the stacks along [010] to form networks (001) which are further anti-parallelly connected by C-H…O(3.382 A,142.9°) andπ…πinteractions extending along [001].Also presented here is a brief study on the C-H…O hydrogen bonds in nitro-substituted benzyl-ideneanilines which can be classified into five types,namely,R12(5)R21(4),R22(8),R12(6),andR22(7),with the first three occurring more often.     

Intramolecular Resonance-assisted Hydrogen Bonds in N-Salicylidene-anilines

In the crystal structures of N-salicylidene-anilines, the ortho-OH group with the central N atom forms a planar six-membered ring through intramolecular hydrogen bonds (Fig. 1). The pseudo-aromatic ring is coplanar with its attached phenyl ring. The resonance strengthens the H-bond through proton transfer between the O and N atoms (Fig.1,Ⅰ←→Ⅱ): dco and dcc become shorter and dCN longer significantly. The d1～d6 are also changed regularly. According to the geometries obtained from X-ray analysis and retrieved from the Cambridge Structural Database (CSD, version 5.21), we believe that the main resonance, at least in solid state, is the molecular keto form (Ⅱ, Fig. 1) instead of the zwitterionic one (Ⅲ, Fig.1).