Ozeryanskii Valery A, Marchenko Andrey V, Pozharskii Alexander F, Filarowski Aleksander, Spiridonova Darya V
Department of Organic Chemistry, Southern Federal University, Zorge str. 7, 344090 Rostov-on-Don, Russian Federation.
Faculty of Chemistry, University of Wroclaw, F. Joliot-Curie 14, 50-383 Wroclaw, Poland.
J Org Chem. 2021 Feb 19;86(4):3637-3647. doi: 10.1021/acs.joc.0c03008. Epub 2021 Feb 2.
A series of previously unknown 2,4,5-tri- and 2,4,5,7-tetrasubstituted 1,8-bis(dimethylamino)naphthalenes and their salts with HBF containing bulky spherically shaped substituents (Me, Br, and SiMe) in the naphthalene ring has been synthesized. Using XRD analysis of 11 samples, the influence of the so-called "buttressing" and "clothespin" effects on their molecular structure and the NHN hydrogen bond geometry in the solid cations were investigated. The combined action of both effects has been shown to significantly increase the compression of the hydrogen bond. As a result, the previous record of the hydrogen bond shortness (N···N = 2.524 Å) has been surpassed in favor of 2.502 Å found for the tetrafluoroborate of 2,4,5,7-tetramethyl-1,8-bis(dimethylamino)naphthalene. The molecular structure of the latter differs by perfect symmetry and practically barrier-free proton transfer in the [NHN] bond. On the basis of the results of quantum-chemical calculations, it is suggested that the value of 2.502 Å likely represents or lies very close to the theoretical limit for the short hydrogen bonds between the amine-type nitrogen atoms.
合成了一系列先前未知的2,4,5-三取代和2,4,5,7-四取代的1,8-双（二甲氨基）萘及其与萘环中含有大体积球形取代基（甲基、溴和三甲基硅基）的氟硼酸的盐。通过对11个样品的X射线衍射分析，研究了所谓的“支撑”和“夹钳”效应对其分子结构以及固体阳离子中NHN氢键几何结构的影响。结果表明，这两种效应的共同作用显著增加了氢键的压缩程度。因此，2,4,5,7-四甲基-1,8-双（二甲氨基）萘的四氟硼酸盐的氢键缩短至2.502 Å，超过了之前的记录（N···N = 2.524 Å）。后者的分子结构具有完美的对称性，且[NHN]键中几乎不存在质子转移障碍。基于量子化学计算结果，推测2.502 Å的值可能代表或非常接近胺型氮原子之间短氢键的理论极限。
