可变温度核磁共振光谱允许直接观察碳酸盐复合物的碳酸盐转移
Alojz Demsar1, Janez Kosmrlj, Sasa Petricek
1Faculty of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, SI-1000 Ljubljana, Slovenia. alojz.demsar@uni-lj.si
Journal of the American Chemical Society
|April 11, 2002
概括
四核复合物在溶液中表现出动态行为,通过可变温度NMR光谱学观察到两个不同的过程. 这些动态涉及碳酸盐协调变化和原子几何变化,为金属有机复合物反应提供了洞察力.
科学领域:
- 协调化学 协调化学
- 有机金属化学 有机金属化学
- 材料科学 材料科学 材料科学
背景情况:
- 合成了四核复合物与碳酸盐和1,3-bis(dimethylamino) -2-propanol (Hbdmap) 连接物.
- 了解金属有机复合物的结构动态和协调模式对于设计新材料和催化剂至关重要.
研究的目的:
- 为了研究四核复合物的溶液状态结构动力学[Zn(4) ((bdmap) ((2) ((OOCR) ((6))) (R = Me, Et).
- 使用可变温度NMR光谱学阐明观察到的动态过程的机制.
- 为了确定与这些动态转换相关的激活参数.
主要方法:
- 四核复合物的合成[Zn(4)(bdmap) ((2)(OOCR) ((6)) ] (R = Me, Et). 它们的组分是:
- 通过X射线晶体学确定固态结构 (对于同位素1a和2a).
- 可变温度 (VT) 1H和13C的NMR光谱在各种化溶剂 (THF-d8,CDCl3,CD2Cl2) 中.
- 对VT NMR光谱进行线形分析,以确定激活参数 (ΔH 和 ΔS).
主要成果:
- 复合体1和2的四核结构被保留在溶液中.
- 确定了两种不同的动态过程:低温 (LT) 动态,涉及碳酸盐协调模式相互转换 (mu-1,2和mu-1,1) 和高温 (HT) 动态,涉及原子协调几何变化.
- 在不同的溶剂中确定了LT和HT动态的激活参数,揭示了依赖溶剂的HT动态.
- 一个聚合物链结构,[Zn(4) ((bdmap) ((2) ((OOCMe) ((6))) n (1-catena),是从复合物1.的二甲溶液结晶出来的.
结论:
- 这些四核复合物的动态行为归因于"碳酸盐转移"机制,涉及碳酸盐桥梁模式和协调的变化.
- 观察到的LT和HT动态为这些金属有机框架的流动性提供了详细的见解.
- 聚合物链结构 (1-catena) 的形成突出了这些离散四核单元自组装和扩展网络形成的潜力.
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