Bosch Eric, Bowling Nathan P
Chemistry and Biochemistry Department, Missouri State University, 901 South National Avenue, Springfield, MO 65897, USA.
Department of Chemistry, University of Wisconsin-Stevens Point, 2101 Fourth Avenue, Stevens Point, WI 54481, USA.
Acta Crystallogr C Struct Chem. 2024 Sep 1;80(Pt 9):553-561. doi: 10.1107/S205322962400771X. Epub 2024 Aug 13.
The structures of a series of 2:1 cocrystals formed between 4-(dimethylamino)pyridine and each of 1,2,4,5-tetrachloro-3,6-diiodobenzene, 2CHN·CClI, 1,2,4,5-tetrabromo-3,6-diiodobenzene, 2CHN·CBrI, 1-bromo-4-iodo-2,3,5,6-tetrafluorobenzene, 2CHN·CBrFI, and 1,2-dibromo-4,5-difluoro-3,6-diiodobenzene, 2CHN·CBrFI, are reported. In all five structures, the core halogen-bonded 2:1 trimolecular units have geometrically similar parameters, with the central halogen-bond donor flanked by two pyridine halogen-bond acceptors twisted with respect to the central halogen-bond donor at angles ranging from 76 to 86°. The I...N halogen-bond separations are all short, ranging from 73.3 to 76.7% of the sum of the van der Waals radii, while the C-I...N bond angles are essentially linear. The Br...N halogen-bond separation in the cocrystal formed with 1-bromo-4-iodo-2,3,5,6-tetrafluorobenzene is 80.4% of the sum of the van der Waals radii. Subtle differences in the crystal packings are attributed to the role of secondary C-H...π and weak π-type interactions with chloro and bromo substituents. The cocrystals 2CHN·CClI and 2CHN·CBrI are isomorphous.
报道了4-（二甲基氨基）吡啶与1,2,4,5-四氯-3,6-二碘苯（2CHN·CClI）、1,2,4,5-四溴-3,6-二碘苯（2CHN·CBrI）、1-溴-4-碘-2,3,5,6-四氟苯（2CHN·CBrFI）以及1,2-二溴-4,5-二氟-3,6-二碘苯（2CHN·CBrFI）形成的一系列2:1共晶体的结构。在所有这五种结构中，核心卤素键合的2:1三分子单元具有几何形状相似的参数，中心卤素键供体两侧是两个吡啶卤素键受体，它们相对于中心卤素键供体扭转的角度范围为76°至86°。I...N卤素键间距均较短，范围为范德华半径总和的73.3%至76.7%，而C-I...N键角基本呈线性。与1-溴-4-碘-2,3,5,6-四氟苯形成的共晶体中的Br...N卤素键间距为范德华半径总和的80.4%。晶体堆积中的细微差异归因于二级C-H...π以及与氯和溴取代基的弱π型相互作用的作用。共晶体2CHN·CClI和2CHN·CBrI是同构的。
