波谱学杂志 ›› 2001, Vol. 18 ›› Issue (4): 321-328.

• 研究论文 • 上一篇    下一篇

四卤化锡混合物中受扩散控制的卤原子交换动力学研究

张永洪, 毛希安*   

  1. 中国科学院武汉物理与数学研究所,波谱与原子分子物理国家重点实验室,武汉 430071
  • 收稿日期:2001-08-02 修回日期:2001-09-03 出版日期:2001-12-05 发布日期:2001-12-05
  • 作者简介:张永洪(1970-),男,博士研究生.*通讯联系人.
  • 基金资助:

    国家自然科学基金资助项目(No.29725307).

NMR STUDY OF DIFFUSION-CONTROLLED EXCHANGE OF HALOGENS IN THE MIXTURES OF TIN (IV) TETRAHALIDES

ZHANG Yong-hong, MAO Xi-an*   

  1. State Key Laboratory of Magnetic Resonance and Atomic Molecular Physics, Wuhan Institute of Physics & Mathematics, The Chinese Academy of Sciences, Wuhan 43007 1, China
  • Received:2001-08-02 Revised:2001-09-03 Online:2001-12-05 Published:2001-12-05
  • About author:*Correspondence author
  • Supported by:

    国家自然科学基金资助项目(No.29725307).

摘要:

119Sn NMR 方法研究了四氯化锡和四溴化锡混合物(1∶1, 摩尔比)交换体系在不同条件下的动力学性质. 测定了在不同浓度的氘代氯仿溶液中5个交换组份的表观纵向弛豫时间(T1)及5个组份相互间的交换速率常数(k),结果表明交换速率常数与表观纵向弛豫速率成正比关系;同时,根据119Sn 1D NMR信号的线宽估测了有效横向弛豫时间(T*2),并由T1/T*2推断在所研究的体系中分子的运动属NMR慢运动极限. 从实验结果可推断在所研究的复杂交换体系中5个组份间的交换与分子自扩散运动有关,即化学交换与交换主体的扩散运动有必然的联系.

关键词: 四卤化锡,  119Sn NMR, 化学交换, 弛豫速率, 扩散运动

Abstract:

The dynamics of halogen exchange in the mixtures of SnCl4 and SnBr4 at di ffer ent concentrations were studied by using 119Sn NMR spectroscopy. Th e spin lattice relaxation times (T1) and the exchange rate constants (k) were measur ed. The res ults show that the magnetization exchange rate constants in this system are prop ortional to the apparent relaxation rates. It is believed that the system is in  the slow motion limit, since the T1/T2 ratio is very large. Theories ind icate th at the spin-lattice relaxation times are proportional to the molecular reorien ta tion correlation time and the correlation time is related to diffusion. It can be concluded that halogen exchange in this system is “diffusion-related”.

Key words: Tin(IV) tetrahalides,  119Sn NMR,  Chemical exchange,  Relaxation rate,  Self-diffusion

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