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Formation Mechanisms, Structure, Solution Behavior, and Reactivity of Aminodiborane
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2015-09-17 , DOI: 10.1021/jacs.5b08033 Huizhen Li 1 , Nana Ma 1 , Wenjuan Meng 1 , Judith Gallucci , Yongqing Qiu 2 , Shujun Li 1 , Qianyi Zhao 1 , Jie Zhang 1 , Ji-Cheng Zhao , Xuenian Chen 1
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2015-09-17 , DOI: 10.1021/jacs.5b08033 Huizhen Li 1 , Nana Ma 1 , Wenjuan Meng 1 , Judith Gallucci , Yongqing Qiu 2 , Shujun Li 1 , Qianyi Zhao 1 , Jie Zhang 1 , Ji-Cheng Zhao , Xuenian Chen 1
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A facile synthesis of cyclic aminodiborane (NH2B2H5, ADB) from ammonia borane (NH3·BH3, AB) and THF·BH3 has made it possible to determine its important characteristics. Ammonia diborane (NH3BH2(μ-H)BH3, AaDB) and aminoborane (NH2BH2, AoB) were identified as key intermediates in the formation of ADB. Elimination of molecular hydrogen occurred from an ion pair, [H2B(NH3) (THF)](+)[BH4](-). Protic-hydridic hydrogen scrambling was proved on the basis of analysis of the molecular hydrogen products, ADB and other reagents through (2)H NMR and MS, and it was proposed that the scrambling occurred as the ion pair reversibly formed a BH5-like intermediate, [(THF)BH2NH2](η(2)-H2)BH3. Loss of molecular hydrogen from the ion pair led to the formation of AoB, most of which was trapped by BH3 to form ADB with a small amount oligomerizing to (NH2BH2)n. Theoretical calculations showed the thermodynamic feasibility of the proposed intermediates and the activation processes. The structure of the ADB·THF complex was found from X-ray single crystal analysis to be a three-dimensional array of zigzag chains of ADB and THF, maintained by hydrogen and dihydrogen bonding. Room temperature exchange of terminal and bridge hydrogens in ADB was observed in THF solution, while such exchange was not observed in diethyl ether or toluene. Both experimental and theoretical results confirm that the B-H-B bridge in ADB is stronger than that in diborane (B2H6, DB). The B-H-B bridge is opened when ADB and NaH react to form sodium aminodiboronate, Na[NH2(BH3)2]. The structure of the sodium salt as its 18-crown-6 ether adduct was determined by X-ray single crystal analysis.
中文翻译：
氨基二硼烷的形成机理、结构、溶液行为和反应性
由氨硼烷 (NH3·BH3, AB) 和 THF·BH3 轻松合成环状氨基乙硼烷 (NH2B2H5, ADB) 使得确定其重要特性成为可能。氨乙硼烷 (NH3BH2(μ-H)BH3, AaDB) 和氨基硼烷 (NH2BH2, AoB) 被确定为形成 ADB 的关键中间体。分子氢的消除发生在离子对 [H2B(NH3) (THF)](+)[BH4](-) 中。通过（2）H NMR和MS对分子氢产物、ADB和其他试剂的分析证明了质子氢加扰，并提出该加扰发生在离子对可逆地形成类BH5中间体时, [(THF)BH2NH2](η(2)-H2)BH3。离子对失去分子氢导致形成 AoB，其中大部分被 BH3 捕获形成 ADB，少量低聚为 (NH2BH2)n。理论计算表明所提出的中间体和活化过程的热力学可行性。通过X射线单晶分析发现ADB·THF配合物的结构是ADB和THF的锯齿状链的三维阵列，由氢和二氢键维持。在 THF 溶液中观察到 ADB 中末端和桥氢的室温交换，而在乙醚或甲苯中未观察到这种交换。实验和理论结果均证实 ADB 中的 BHB 桥比乙硼烷 (B2H6, DB) 中的强。当 ADB 和 NaH 反应形成氨基二硼酸钠 Na[NH2(BH3)2] 时，BHB 桥打开。通过 X 射线单晶分析确定了钠盐的 18-冠-6 醚加合物的结构。
更新日期：2015-09-17
中文翻译：
氨基二硼烷的形成机理、结构、溶液行为和反应性
由氨硼烷 (NH3·BH3, AB) 和 THF·BH3 轻松合成环状氨基乙硼烷 (NH2B2H5, ADB) 使得确定其重要特性成为可能。氨乙硼烷 (NH3BH2(μ-H)BH3, AaDB) 和氨基硼烷 (NH2BH2, AoB) 被确定为形成 ADB 的关键中间体。分子氢的消除发生在离子对 [H2B(NH3) (THF)](+)[BH4](-) 中。通过（2）H NMR和MS对分子氢产物、ADB和其他试剂的分析证明了质子氢加扰，并提出该加扰发生在离子对可逆地形成类BH5中间体时, [(THF)BH2NH2](η(2)-H2)BH3。离子对失去分子氢导致形成 AoB，其中大部分被 BH3 捕获形成 ADB，少量低聚为 (NH2BH2)n。理论计算表明所提出的中间体和活化过程的热力学可行性。通过X射线单晶分析发现ADB·THF配合物的结构是ADB和THF的锯齿状链的三维阵列，由氢和二氢键维持。在 THF 溶液中观察到 ADB 中末端和桥氢的室温交换，而在乙醚或甲苯中未观察到这种交换。实验和理论结果均证实 ADB 中的 BHB 桥比乙硼烷 (B2H6, DB) 中的强。当 ADB 和 NaH 反应形成氨基二硼酸钠 Na[NH2(BH3)2] 时，BHB 桥打开。通过 X 射线单晶分析确定了钠盐的 18-冠-6 醚加合物的结构。
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