STRUCTURE OF ALPHA-(DIMETHYLAMINO)BENZYLLITHIUM IN SOLUTION - DYNAMIC EQUILIBRIUM BETWEEN AN ETA-1 AND AN ETA-3 SPECIES
STRUCTURE OF ALPHA-(DIMETHYLAMINO)BENZYLLITHIUM IN SOLUTION - DYNAMIC EQUILIBRIUM BETWEEN AN ETA-1 AND AN ETA-3 SPECIES
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DOI：
10.1002/cber.19921250730
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发表时间：
1992-07-01
期刊：
影响因子：
--
通讯作者：
KALINOWSKI, HO
中科院分区：
文献类型：
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作者：
AHLBRECHT, H;HARBACH, J;KALINOWSKI, HO
在四氢呋喃中观察到的随温度变化的H-1和C-13-核磁共振光谱位移表明高温ETA-3和低温ETA-1物种之间存在平衡。MNDO计算符合这一观点，HOESY实验也证明了这一点。平衡受溶剂化或络合、溶剂的低Lewis碱性或有利于ETA-3的双齿配体、ETA-1物种的高Lewis碱性或三齿配体的控制。估算了平衡常数和速率常数，并根据它们与温度的关系计算了平衡和活化势垒的热力学。
Temperature-dependent H-1- and C-13-NMR-spektroscopic shifts observed in tetrahydrofuran are indicative of an equilibrium between a high-temperature eta-3 and a low-temperature eta-1 species. MNDO calculations are in accord with this view, and HOESY experiments proof it, too. The equilibrium is controled by solvation or complexation, low Lewis basicity of the solvent or bidentate ligands favoring the eta-3, high Lewis basicity or tridentate ligands the eta-1 species. Equilibrium as well as rate constants have been estimated, and from their temperature dependence the thermodynamics of the equilibrium and the activation barriers were calculated.