Structural systematics and conformational analyses of a 3 × 3 isomer grid of nine N-(tolyl)pyridinecarboxamides and three chlorinated relatives
作者:Pavle Mocilac、John F. Gallagher
DOI:10.1039/c1ce05169e
日期:——
A 3 × 3 isomer grid of nine N-(tolyl)pyridinecarboxamides (NxxM, x = para-/meta-/ortho-) integrating crystal structure analyses, ab initio calculations (gas phase and PCM-SMD solvated in CH2Cl2, H2O) and conformational studies is described. Three 5-Cl-NoxM derivatives (side-products from the NoxM syntheses) and NmpFM (a 50 : 50 mixture of NmpF and NmpM) are reported. The six NpxM/NmxM isomers aggregate via N–H⋯N or N–H⋯OC hydrogen bonds, whereas the six NoxM/5-Cl-NoxM structures exhibit intramolecular N–H⋯N interactions influencing co-planarity. The NmmM isomer is isomorphous and isostructural with its bridge-flippedMmm isomer providing a rare case of isostructuralism between such isomers. Our objectives are to (a) understand correlations between the p-/m-/o-N/CH3 substituent permutations with solid state molecular conformations and supramolecular aggregation, (b) explain the influence of molecular conformation on inter/intramolecular interactions, (c) correlate physico-chemical properties and (d) compare and rationalise differences between crystal and calculated structures.
本文介绍了九种 N-(甲苯基)吡啶羧酰胺(NxxM,x = 对位/甲位/正位)的 3 × 3 异构体网格,综合了晶体结构分析、ab initio 计算(气相和 PCM-SMD 溶于 CH2Cl2、H2O)和构象研究。报告了三种 5-Cl-NoxM 衍生物(NoxM 合成的副产品)和 NmpFM(NmpF 和 NmpM 的 50 : 50 混合物)。六种 NpxM/NmxM 异构体通过 N-H⋯N 或 N-H⋯OC 氢键聚合,而六种 NoxM/5-Cl-NoxM 结构则表现出影响共平面性的分子内 N-H⋯N 相互作用。NmmM 异构体与其桥翻转的 Mmm 异构体同构,提供了此类异构体之间同构的罕见案例。我们的目标是:(a) 了解 p-/m-/o-N/CH3 取代基排列与固态分子构象和超分子聚集之间的相关性;(b) 解释分子构象对分子间/分子内相互作用的影响;(c) 关联物理化学性质;(d) 比较晶体结构和计算结构之间的差异并使之合理化。