Center for Materials Crystallography, Interdisciplinary Nanoscience Center (iNANO), and Department of Chemistry, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark.
Laboratory of Crystallography, DQMP, University of Geneva, 1211 Geneva, Switzerland.
Chem Soc Rev. 2017 Mar 6;46(5):1565-1634. doi: 10.1039/c6cs00705h.
A wide variety of metal borohydrides, MBH, have been discovered and characterized during the past decade, revealing an extremely rich chemistry including fascinating structural flexibility and a wide range of compositions and physical properties. Metal borohydrides receive increasing interest within the energy storage field due to their extremely high hydrogen density and possible uses in batteries as solid state ion conductors. Recently, new types of physical properties have been explored in lanthanide-bearing borohydrides related to solid state phosphors and magnetic refrigeration. Two major classes of metal borohydride derivatives have also been discovered: anion-substituted compounds where the complex borohydride anion, BH, is replaced by another anion, i.e. a halide or amide ion; and metal borohydrides modified with neutral molecules, such as NH, NHBH, NH, etc. Here, we review new synthetic strategies along with structural, physical and chemical properties for metal borohydrides, revealing a number of new trends correlating composition, structure, bonding and thermal properties. These new trends provide general knowledge and may contribute to the design and discovery of new metal borohydrides with tailored properties towards the rational design of novel functional materials. This review also demonstrates that there is still room for discovering new combinations of light elements including boron and hydrogen, leading to complex hydrides with extreme flexibility in composition, structure and properties.
在过去的十年中，已经发现并描述了各种各样的金属硼氢化物 (MBH)，揭示了极其丰富的化学性质，包括引人入胜的结构灵活性以及广泛的组成和物理性质。由于金属硼氢化物具有极高的氢密度以及在电池中用作固态离子导体的潜在用途，因此它们在储能领域越来越受到关注。最近，在与固态磷光体和磁制冷相关的镧系元素硼氢化物中，已经探索了新型物理性质。还发现了两种主要类型的金属硼氢化物衍生物：阴离子取代化合物，其中复杂的硼氢阴离子 BH 被另一个阴离子取代，例如卤化物或酰胺离子；以及用中性分子（例如 NH、NHBH、NH 等）修饰的金属硼氢化物。在这里，我们综述了金属硼氢化物的新合成策略以及结构、物理和化学性质，揭示了一些与组成、结构、键合和热性质相关的新趋势。这些新趋势提供了一般知识，并可能有助于设计和发现具有定制性质的新型金属硼氢化物，以实现新型功能材料的合理设计。本综述还表明，仍然有空间发现包括硼和氢在内的轻元素的新组合，从而形成在组成、结构和性质上具有极大灵活性的复杂氢化物。
