高等学校化学学报 ›› 1983, Vol. 4 ›› Issue (4): 469-475.

• 论文 • 上一篇    下一篇

氮氧自由基的研究(Ⅴ)——哌啶类氮氧自由基4-位取代基对ESR超精细分裂的影响

刘有成, 刘中立, 王玉琨   

  1. 兰州大学化学系
  • 收稿日期:1982-02-08 出版日期:1983-08-24 发布日期:1983-08-24

STUDIES ON NITROXIDES (Ⅴ)——THE EFFECT OF 4-SUBSTITUENT ON THE ESR hfs CONSTANTS OF PIPERIDINE NITROXIDES

Liu Youcheng, Liu Zhongli, Wang Yukun   

  1. Department of Chemistry, University of Lanzhou, Lanzhou
  • Received:1982-02-08 Online:1983-08-24 Published:1983-08-24

摘要: 本文合成了六个4-位具有不同取代基(O,OH,Cl,Br,I,H)的2,2,6,6-四甲基哌啶-1-氧自由基,在正己烷及乙二醇中分别测定了它们的ESR各向同性hfs常数αN,发现在这两种溶剂中,αN均与取代基原子的电负性线性相关,但直线的斜率不同。EHMO计算对实验结果作出了满意的解释。

Abstract: Six differently 4-substituted 2, 2, 6, 6-tetramethylpiperidyl-N-oxides were synthesized and their ESR hfs constants aN determined in n-hexane and glycol respectively. It is shown that an approximate linear correlation between αN and Pauling's electronegativity x of the 4-substituent is present for both solvents, but the slopes of the αN-x straight lines are very different. Based on the EHMO calculations it is proposed that the effect of 4-substituent on aN may be caused by a kind of field effect which affects the spin density (i. e., the electron distribution in the frontier orbital) and the "out of plane angle" (i. e., the hybridization of the N atom). The solvent effect is explained in terms of the EHMO calculations, too.