Biphenylene. Internuclear distances and their root mean square amplitudes of vibration
Biphenylene. Internuclear distances and their root mean square amplitudes of vibration
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亚联苯。
DOI：
10.1021/ja00811a014
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发表时间：
1974
影响因子：
15
通讯作者：
S. Bauer
中科院分区：
文献类型：
--
作者：
A. Yokozeki;C. Wilcox;S. Bauer
通过电子衍射研究了气相中联苯撑的分子结构；样品保持在145。径向分布曲线的分辨率表明这些分子具有平面构象。基于假定的 D2h 对称性和源自 X 射线晶体结构的相对键长，分子散射函数的最小二乘分析给出了原子间距离的以下 rs 值：(CC) aT= 1.418±0.003 Á，Ci-C8b= 1.372±0.012 A，Ci-C2= 1.428±0.012 Á， C2-C3=1.370±0.015A，C4-C4b=1.524±0.006A，C4a-C8b=1.432±0.018A，CH=1.096±0.009A，zC8b-Ci-C2=115.0±1.2，zCi-Cr-Ci= 122.5±1.2，zC4a-C8b-C1=122.5±0.6。在上面的列表中，角度是在热像表示中定义的，收缩校正是在最小二乘程序中插入的。列出的不确定性代表估计的误差限度。结构参数与晶体结构分析得出的相应值非常一致。苯环扭曲，“键固定”明显存在。C4a-C4b 距离几乎与正常单键一样长，而 C8b-Ci 间距明显短于苯中的 CC 间距。结构的另一个特征是相对较小的角度 zC8b-Ci-C2。观察到的和计算的均方振幅之间的比较表明，由于较大的角，该分子可能是“准平面”的。面外振动模式的振幅。
The molecular structure of biphenylene in the gas phase was investigated by electron diffraction; the sample was maintained at 145. Resolution of the radial distribution curve indicated that these molecules have a planar conformation. On the basis of the assumed D2h symmetry and the relative bond lengths derived from the X-ray crystal structure, a least-squares analysis of the molecular scattering function gave the following rs values for the interatomic distances:(CC) aT= 1.418±0.003 Á, Ci-C8b= 1.372±0.012 A, Ci-C2= 1.428±0.012 Á, C2-C3= 1.370±0.015 Á, C4-C4b= 1.524±0.006 A, C4a-C8b= 1.432±0.018 A, CH= 1.096±0.009 Á, zC8b-Ci-C2= 115.0±1.2, zCi-Cr-Ci= 122.5±1.2, zC4a-C8b-C1= 122.5±0.6. In the above list the angles were defined in thera representation and shrinkage corrections were inserted in the least-squares program. The listed uncertainties represent estimated limits of error. The structural parameters are in good agreement with corresponding values derived from a crystal structure analysis. The benzene rings are distorted, and “bond fixa-tion’’is clearly present. The C4a-C4b distances are almost as long as in a normal single bond while the C8b-Ci separations are definitely shorter than the CC separation in benzene. Another characteristic feature of the struc-ture is the relatively small angle, zC8b-Ci-C2. Comparison between the observed and calculated mean square amplitudes suggests that this molecule may be “quasiplanar” due to the large amplitudes of the out-of-planevibrational modes.