<sup>77</sup>Se NMR Chemical Shifts of 9-(Arylselanyl)triptycenes: New Standard for Planar Structures of ArSeR and Applications to Determine the Structures in Solutions
作者:Takashi Nakamoto、Satoko Hayashi、Waro Nakanishi
DOI:10.1021/jo801786j
日期:2008.12.5
that of 1-(arylselanyl)anthraquinones (3 (pd)). Sets of delta(Se) of 1 and 2 must serve as the standard for pl and that of 3 does for pd in solutions. Structures of various ArSeR in solutions are determined from the viewpoint of the orientational effect based on the standard delta(Se) of 1-3. While the structure of 2-methyl-1-(arylselanyl)naphthalenes is concluded to be all pl in solutions, those of 8-chloro-
should supply the planar structure (pl) around the p-YC6H4Se (ArSe) group in the ground state, irrespective of the p-Y substituents. 1 with Y = H (a), NMe2 (b), OMe (c), Cl (d), CN (e) and NO2 (f) are prepared. Structures of 1a–d and 1f are determined by X-ray analysis and dynamic 1H NMR spectroscopy is applied to 1a, 1c, 1e and 1f. For convenience of discussion, the structure of 1 is defined as follows:
9-(芳基杂戊基)三联烯(1:p -YC 6 H 4 SeTpc)应在基态下围绕p -YC 6 H 4 Se(ArSe )基团提供平面结构(pl),而与p -Y取代基无关。1与Y = H(一),NME 2(b),OME(Ç),CL(d),CN(ë)和NO 2(˚F)制备。的结构图1A-d和1F是通过X射线分析和动态确定的1 H NMR光谱适用于1a, 1c, 1e和1f。为了便于讨论,将1的结构定义如下:将1中的三联基周围的构象体称为A,其中Se–C Ar键位于三联基的两个苯基平面之间的等分区域中,它为B其中键在三苯甲基的苯基平面上。Ar基团的构象异构体称为pl,其中Se–C Tpc键位于Ar平面上,而如果键垂直于该平面则为pd。的结构通过X射线分析确认1为基态(A:pl)。1(A:pl)通过过渡状态1(B:pd)转换为等效齿轮(换档过程)。活化能是通过测定动态1 H NMR光谱:值是36