Twist angles and rotational energy barriers of biphenyl and substituted biphenyls
Twist angles and rotational energy barriers of biphenyl and substituted biphenyls
复制标题
DOI：
10.1021/jp0122124
复制
发表时间：
2002-04-18
影响因子：
2.9
通讯作者：
Grein, F
中科院分区：
文献类型：
--
作者：
Grein, F
用B3LYP/6 - 311 + G * 等方法计算了联苯、2-卤代联苯、2，2 ′-二卤代联苯和3，3 ′-二卤代联苯的扭转角和扭转能。与现有的气相和X射线数据的结果进行了比较。2，2'-二氟BP在57.9度和128.9度处具有旋转双极小值，而其他2，2'-二卤BP在二面角84.9度至94.8度处具有单一极小值。所有3，3 '-二卤BP在约45度和135度处都有双最小值。还计算了2，2'-二甲基BP和全氟以及全氯BP的优化扭曲角和能垒。大多数结构是由空间效应来解释的。然而，对于2，2'-二卤素BP，吸引力似乎也起作用，如2，2'-二氯BP的二面角远低于90度所证明的。
Using B3LYP/6-311+G* and other methods, twist angles and torsional energies were obtained for biphenyl (BP), 2-halogen BPs, 2,2'-dihalogen BPs, and 3,3'-dihalogen BPs, the halogens ranging from F to I. The results were compared with available gas phase and X-ray data. 2,2'-difluoro BP has a rotational double minimum, at 57.9 and 128.9degrees, whereas the other 2,2'-dihalogen BPs have a single minimum at dihedral angles ranging from 84.9 to 94.8degrees. All 3,3'-dihalogen BPs have a double minimum at about 45 and 135degrees. Optimized twist angles and energy barriers were also calculated for 2,2'-dimethyl BP and for perfluoro as well as perchloro BP. Most structures are accounted for by steric effects. For 2,2'-dihalogen BPs, however, attractive forces also appear to play a role, as evidenced by the dihedral angle of 2,2'-dichloro BP lying well below 90degrees.