THE CRYSTAL AND MOLECULAR-STRUCTURE OF TRIS(SUBSTITUTED AMINO) SULFONIUM IONS
THE CRYSTAL AND MOLECULAR-STRUCTURE OF TRIS(SUBSTITUTED AMINO) SULFONIUM IONS
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DOI：
10.1021/ja00236a028
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发表时间：
1987-01-21
影响因子：
15
通讯作者：
GUGGENBERGER, LJ
中科院分区：
文献类型：
--
作者：
FARNHAM, WB;DIXON, DA;GUGGENBERGER, LJ
本文报道了一系列三（二甲氨基）锍阳离子盐（甲基-TAS）的合成和晶体结构。甲基-TAS阳离子的结构非常相似，具有近似Cs对称性，含有两个等价的（CH_3）_2N ~“基团和一个唯一的（CH_3）_2N ~'基团。该结构的特征在于长SN'键距为1.689 A，两个短SN”键距为1.615 A。N”-SN”键角较大，为115.4，而两个N '-SN”键角较小，为99.2，与其他锍离子相似。独特的氨基是金字塔形的，而等效的氨基近似是平面的。结果表明SN”键具有多键特征。用大基组的从头计算方法对S（NH 2）3+进行了分子轨道计算，证实了所观测到的X射线晶体结构.在S+反演的表面的详细构象分析。分析计算的红外频率和强度，这些结果与观察到的结构是一致的。发现硫是相当正的，q（S）= 0.92e。还介绍了一种三环TAS衍生物的晶体结构。环应变导致偏离甲基-TAS的优选结构。观察到一个非常短的标称非键合SO距离为2.55 A。
The synthesis and crystal structures determined by X-ray diffraction techniques for a number of salts of the tris (dimethylamino) sulfonium cation (methyl-TAS) are reported. The structures of the methyl-TAS cation are all very similar, and the cation possesses approximate Cs symmetry with two equivalent (CH3) 2N" groupsand one unique (CH3) 2N'group. The structure is characterized by a long SN'bond distance of 1.689 A and two short SN" bond distances of 1.615 A. The N"-SN" bond angle is large, 115.4, while the two N'-SN" bond angles are smaller, 99.2, similar to those in other sulfonium ions. The unique amino group is pyramidal, and the equivalent amino groups are approximately planar. The results suggest multibonding character in the SN" bonds. Ab initio molecular orbital calculations on S (NH2) 3+ with a large basis set confirm the observed X-ray crystalstructure. A detailed conformational analysis of the surface for inversion at S+ is presented. Analytically calculated infrared frequencies and intensities are presented, and these results are consistent with the observed structures. The sulfur is found to be quite positive, q (S)= 0.92 e. The crystal structure of a tricyclic TAS derivative is also presented. Ring strain causes deviations from the preferred structure found for methyl-TAS. A very short nominally nonbonded SO distance of 2.55 A is observed.