Unusual C-H center dot center dot center dot pi Interactions in the Structure of 3,4,5-Trimethoxy-N-p-tolylbenzamide

作者：Saeed Aamer; Simpson Jim^*

来源：Journal of Chemical Crystallography, 2013, 43(1): 51-57.

DOI：10.1007/s10870-012-0386-6

• Benzamides
• Tri-methoxy benzene derivatives
• Spectroscopic characterisation
• Crystal structure
• Hydrogen bonding
• C-H center dot center dot center dot pi interactions

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 P2(1), with a = 5.1065(7) ; b = 13.9148(18) ; c = 11.2054(14) ; beta = 103.118(7)A degrees; Z = 2. In the X-ray structure packing is predictably influenced by strong N-H center dot center dot center dot O hydrogen bonds, augmented by C-H center dot center dot center dot 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 center dot center dot center dot 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 center dot center dot center dot pi 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. %26lt;br%26gt;The structure of 3,4,5-trimethoxy-N-p-tolylbenzamide is notable for the occurrence of C-H center dot center dot center dot pi interactions involving two hydrogen atoms from each of the 3- and 5-methoxy groups.

• 出版日期2013-1