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Reversible Coordination of H2 by a Distannyne
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2018-01-05 , DOI: 10.1021/jacs.7b11798
Shuai Wang 1 , Tobias J. Sherbow 1 , Louise A. Berben 1 , Philip P. Power 1
Affiliation  

The terphenyl tin(II) hydride [AriPr4Sn(μ-H)]2 (1) (AriPr4 = C6H3-2,6(C6H3-2,6-iPr2)2) was shown to form an equilibrium with the distannyne AriPr4SnSnAriPr4 (2) and H2 in toluene at 80 °C. The equilibrium constant and Gibbs free energy for the dissociation of H2 are 2.23 × 10-4 ± 4.9% and 5.89 kcal/mol ± 0.68%, respectively, by 1H NMR spectroscopy and 2.33 × 10-4 ± 6.2% and 5.86 kcal/mol ± 0.73%, respectively, by UV-vis spectroscopy, indicating that the hydride 1 is strongly favored. Further heating of 2 at ca. 100 °C afforded the known pentagonal-bipyramidal Sn7 cluster Sn5(SnAriPr4)2 (3). Mechanistic studies show that 3 is formed from distannyne 2, which is generated from 1. The order of the reaction for the conversion of 2 into 3 was found to be zero, and the rate constant is 1.77 × 10-5 M s-1 at 100 °C. Hydride 1 was further characterized by cyclic voltammetry, and its pKa was found to be 18.8(2) via titration with 1,8-diazabicyclo[5.4.0]undec-7-ene. The bond dissociation free energy was estimated to be 51.1 kcal/mol ± 3.4% on the basis of its pKa and reduction potential. Studies with deuterium indicate ready exchange of D2 with the hydrides in 1.

中文翻译:

Distannyne 对 H2 的可逆配位

三联苯锡 (II) 氢化物 [AriPr4Sn(μ-H)]2 (1) (AriPr4 = C6H3-2,6(C6H3-2,6-iPr2)2) 与二锡烷 AriPr4SnSnAriPr4 (2 ) 和 80 °C 的甲苯中的 H2。H2 解离的平衡常数和吉布斯自由能分别为 2.23 × 10-4 ± 4.9% 和 5.89 kcal/mol ± 0.68%,通过 1H NMR 光谱和 2.33 × 10-4 ± 6.2% 和 5.86 kcal/mol紫外-可见光谱分别为±0.73%,表明氢化物1受到强烈青睐。进一步加热 2 在约。100 °C 得到已知的五边形双锥 Sn7 簇 Sn5(SnAriPr4)2 (3)。机理研究表明,3 是由二锡烷 2 形成的,二锡烷 2 是由 1 生成的。 发现将 2 转化为 3 的反应阶数为零,速率常数为 1.77 × 10-5 M s-1 在100℃。氢化物 1 进一步通过循环伏安法表征,通过用 1,8-二氮杂双环 [5.4.0] undec-7-ene 滴定发现其 pKa 为 18.8(2)。根据其 pKa 和还原电位,键解离自由能估计为 51.1 kcal/mol ± 3.4%。对氘的研究表明 D2 可以与 1 中的氢化物轻松交换。
更新日期:2018-01-05
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