Unusual C–H···π Interactions in the Structure of 3,4,5-Trimethoxy-N-p-tolylbenzamide
作者:Aamer Saeed、Jim Simpson
DOI:10.1007/s10870-012-0386-6
日期:2013.1
3,4,5-trimethoxy-N-p-tolylbenzamide, C17H19NO4, (1), is a benzanilide derivative derived from p-toluidine and 3,4,5-trimethoxybenzoyl chloride. The structure was identified from spectroscopic and elemental analysis data and unambiguously confirmed by the single crystal X-ray diffraction studies in space group P21, with a = 5.1065(7) Å; b = 13.9148(18) Å; c = 11.2054(14) Å; β = 103.118(7)°; Z = 2. In the X-ray structure packing is predictably influenced by strong N–H···O hydrogen bonds, augmented by C–H···O contacts generating R 1 2 (6) ring motifs and forming chains of molecules along the b axis. Chains are also linked in a head-to-tail fashion by an additional weak Ar–C–H···O contact involving the tolyl methyl group. A particularly unusual feature of the packing in this structure however, is the extensive contribution of C–H···π interactions, involving two hydrogen atoms from each of the methyl groups of the 3- and 5-methoxy substituents. These link the chains into a three-dimensional network. A CSD investigation of intermolecular interactions involving both phenyl-bound and methoxy methyl groups is also presented. The structure of 3,4,5-trimethoxy-N-p-tolylbenzamide is notable for the occurrence of C–H···π interactions involving two hydrogen atoms from each of the 3- and 5-methoxy groups.
3,4,5-三甲氧基-N-对甲苯甲酰胺,C17H19NO4, (1),是一种苯甲酰苯胺衍生物,衍生自对甲苯胺和 3,4,5-三甲氧基苯甲酰氯。该结构通过光谱和元素分析数据进行鉴定,并通过空间群 P21 中的单晶 X 射线衍射研究明确证实,a = 5.1065(7) Å; b = 13.9148(18) Å; c = 11.2054(14) Å; β = 103.118(7)°; Z = 2。在 X 射线结构中,堆积受到强 N–H…O 氢键的影响,并通过 C–H…O 接触增强,产生 R 1 2 (6) 环基序并形成分子链沿b轴。链还通过涉及甲苯基甲基的附加弱Ar-C-H·O接触以头尾方式连接。然而,这种结构中堆积的一个特别不寻常的特征是C–H·π相互作用的广泛贡献,涉及来自3-和5-甲氧基取代基的每个甲基的两个氢原子。它们将链条连接成三维网络。还介绍了涉及苯基结合和甲氧基甲基的分子间相互作用的 CSD 研究。 3,4,5-三甲氧基-N-对甲苯甲酰胺的结构因涉及 3- 和 5-甲氧基各两个氢原子的 C-H·π 相互作用的发生而引人注目。