小分子硼烷簇和多面体硼烷的热力学水合性质。
Thermodynamic Hydricity of Small Borane Clusters and Polyhedral -Boranes.
机构信息
A. N. Nesmeyanov Institute of Organoelement Compounds and Russian Academy of Sciences (INEOS RAS), 28 Vavilova St, 119991 Moscow, Russia.
Faculty of Chemistry, M.V. Lomonosov Moscow State University, 1/3 Leninskiye Gory, 119991 Moscow, Russia.
出版信息
Molecules. 2020 Jun 25;25(12):2920. doi: 10.3390/molecules25122920.
Thermodynamic hydricity (HDA) determined as Gibbs free energy (ΔG°[H]) of the H detachment reaction in acetonitrile (MeCN) was assessed for 144 small borane clusters (up to 5 boron atoms), polyhedral -boranes dianions [BH], and their lithium salts Li[BH] (n = 5-17) by DFT method [M06/6-311++G(d,p)] taking into account non-specific solvent effect (SMD model). Thermodynamic hydricity values of diborane BH (HDA = 82.1 kcal/mol) and its dianion [BH] (HDA = 40.9 kcal/mol for Li[BH]) can be selected as border points for the range of borane clusters' reactivity. Borane clusters with HDA below 41 kcal/mol are strong hydride donors capable of reducing CO (HDA = 44 kcal/mol for HCO), whereas those with HDA over 82 kcal/mol, predominately neutral boranes, are weak hydride donors and less prone to hydride transfer than to proton transfer (e.g., BH, BH, BH, etc.). The HDA values of -boranes are found to directly depend on the coordination number of the boron atom from which hydride detachment and stabilization of quasi-borinium cation takes place. In general, the larger the coordination number (CN) of a boron atom, the lower the value of HDA.
热力学水合能（HDA）被定义为在乙腈（MeCN）中氢原子脱离反应的吉布斯自由能（ΔG°[H]），通过密度泛函理论（DFT）方法[M06/6-311++G(d,p)]，考虑非特异性溶剂效应（SMD 模型），对 144 个小硼烷簇（最多 5 个硼原子）、多面体硼烷二阴离子[BH]及其锂盐 Li[BH]（n = 5-17）进行了评估。二硼烷 BH（HDA = 82.1 kcal/mol）及其二阴离子[BH]（Li[BH]的 HDA = 40.9 kcal/mol）的热力学水合能值可以作为硼烷簇反应性范围的边界点。HDA 值低于 41 kcal/mol 的硼烷簇是强氢化物供体，能够还原 CO（HCO 的 HDA = 44 kcal/mol），而 HDA 值超过 82 kcal/mol 的硼烷簇，主要是中性硼烷，是弱氢化物供体，与质子转移相比，更不容易发生氢化物转移（例如 BH、BH、BH 等）。-硼烷的 HDA 值被发现直接取决于氢原子脱离和准硼阳离子稳定化的硼原子的配位数。一般来说，硼原子的配位数（CN）越大，HDA 值越低。
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