An extensive library of 77Se chemical shifts have been generated from the NMR measurements on substituted (phenylseleno)benzenes, including 33 new compounds. The variation in chemical shifts cover 265 ppm ranging from 446 to 181 ppm.
Crystal structures have been determined for nine selected representatives of the substituted (phenylseleno)benzenes. The analysis of the crystal structures supported that through-space interactions between selenium and the ortho-substituent observed in the crystal structures also are likely to be present in solution.
The variation in the 77Se NMR chemical shifts can be rationalised from the intramolecular interactions with the substituent in the ortho-position. Furthermore it appears that these ortho-effects are roughly additive, and that it is the actual interactions and not the resulting conformational constraints that are responsible for the variations in the 77Se NMR chemical shifts.
从取代的(苯基
硒)苯的NMR测量中生成了一幅广泛的77Se
化学位移库,包括33种新化合物。
化学位移的变化范围覆盖了265 ppm,从446 ppm到181 ppm不等。
已确定九个选定的取代(苯基
硒)苯的晶体结构。晶体结构的分析支持了在晶体结构中观察到的
硒与邻位取代基之间的空间相互作用在溶液中也可能存在。
77Se NMR
化学位移的变化可以从与邻位取代基的分子内相互作用中进行合理化。此外,这些邻效应似乎是粗略可加的,实际上影响77Se NMR
化学位移变化的是相互作用,而不是由此产生的构象约束。