Charge-Transfer Interaction and Molecular Arrangement in the Crystals of 2-(<i>p</i>-Nitrophenoxy)ethyl Ethers and Amines
作者:Yasuhiro Mazaki、Kiyoshi Mutai
DOI:10.1246/bcsj.68.3247
日期:1995.11
X-Ray crystallographic analysis of the Acceptor-(CH2)2-Donor type compounds, p-O2NC6H4OCH2CH2OAr (Ar = m- and p-Me2NC6H4, and m-Et2NC6H4) and p-O2NC6H4OCH2CH2N(CH3)C6H4OMe-p, has been carried out. Among these, only m-dimethylamino derivative (1) gives dark red prisms in which a close arrangement of the electron-donor and acceptor groups is observed. With regard to the central C–C bond in ArO–C–C–OAr′ or ArO–C–C–NAr′, three of the above-mentioned four compounds show gauche conformation: 1 is the exception. The preference of the gauche , probably characteristic of O–C–C–O (or –N) group, is suggested to be due to a small energy difference between the trans and gauche forms by using the MM2 and the PM3 approximation. Charge-transfer interaction energy in 1 as an intermolecular force is estimated to be barely large enough to make the trans conformation favorable over the gauche.
对受体-(CH2)2-受体型化合物 p-O2NC6H4OCH2CH2OAr(Ar = m- 和 p-Me2NC6H4,以及 m-Et2NC6H4)和 p-O2NC6H4OCH2CH2N(CH3)C6H4OMe-p,进行了 X 射线晶体学分析。在这些衍生物中,只有间二甲基氨基衍生物(1)呈现出暗红色棱柱,其中的电子供体和受体基团排列紧密。关于 ArO-C-C-OAr′ 或 ArO-C-C-NAr′ 中的中心 C-C 键,上述四种化合物中有三种呈现出 "凹凸 "构象:1 是个例外。通过使用 MM2 和 PM3 近似法,我们发现反式和高顺式之间的能量差异较小,这可能是 O-C-C-O(或 -N)基团偏好高顺式的原因。据估计,1 中作为分子间作用力的电荷转移相互作用能量几乎不足以使反式构象优于高切构象。