Interstellar clouds and the outer reaches of protostellar and protoplanetary systems are very cold environments where chemistry is limited to processes that have little or no reaction barrier (in the absence of external energy input). This account reviews what is known about cation–ice reactions, which are not currently incorporated in astrochemical network models. Quantum chemical cluster calculations using density functional theory have shown that barrierless reactions can occur when gas phase cations such as HCO⁺, OH⁺, CH₃⁺, and C⁺ are deposited on an icy grain mantle with energies commensurate with other gas phase species. When cations react with molecules on ice surfaces, the pathways and products often differ significantly from gas phase chemistry due to the involvement of water and other molecules in the ice. The reactions studied to date have found pathways to abundant and important astromolecules such as methanol, formic acid, and carbon dioxide that are very favorable and may be more efficient pathways than gas phase processes. Other products that can be produced include glycolonitrile, its precursors, and related isocyanide compounds. This account describes for the first time ice surface reactions between the carbon cation, C⁺, and two common astromolecules, methanol (CH₃OH) and formic acid (HCOOH), which can yield precursors to glyoxal, hydroxyketene, vinyl alcohol, and acetaldehyde. The quantum chemical methodology used to explore reaction surfaces is also used to predict both vibrational and electronic spectra of reactant and product ices, which offers guidance for possible experimental studies of these reactions. While theoretical calculations indicate that cation–ice reactions are efficient and offer novel pathways to important astrochemical compounds, experimental confirmation would be very welcome. Cations and ice-covered grain mantles are certainly present in cold astrophysical environments. The account concludes with a discussion of how cation–ice reactions could be incorporated into reaction network models of the formation and destruction of molecules in interstellar clouds and protoplanetary systems. Further studies will involve characterizing additional rcactions and more extensive treatment of the most important cation–ice reactions to better ascertain reaction branching outcomes.

中文翻译：

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用于阳离子化学反应的阳离子-冰反应的量子化学簇研究：寻求实验证实

星际云以及原星和原行星系统的外围都是非常寒冷的环境，在这种环境中，化学作用仅限于反应障碍很少或没有反应的过程（在没有外部能量输入的情况下）。该帐户回顾了有关阳离子冰反应的知识，目前尚不将其纳入星化网络模型中。使用密度泛函理论的量子化学簇计算表明，当气相阳离子（例如HCO ⁺，OH ⁺，CH ₃ ⁺和C ^+）发生无阻反应时沉积在冰晶状的地幔上，其能量与其他气相物质相当。当阳离子与冰表面上的分子反应时，由于水和其他分子的参与，这些途径和产物通常与气相化学反应显着不同。迄今为止研究的反应已经发现了通往大量重要的无规分子（例如甲醇，甲酸和二氧化碳）的途径，这是非常有利的，并且可能比气相过程更有效。可以生产的其他产品包括乙醇腈，其前体和相关的异氰化物。该说明首次描述了碳阳离子C ⁺与两种常见的无规分子甲醇（CH ₃OH）和甲酸（HCOOH），可以生成乙二醛，羟基烯酮，乙烯醇和乙醛的前体。用于探索反应表面的量子化学方法还用于预测反应物和产物冰的振动光谱和电子光谱，这为这些反应的可能实验研究提供了指导。尽管理论计算表明阳离子-冰的反应是有效的，并且为重要的化学化合物提供了新颖的途径，但实验证实将是非常受欢迎的。在寒冷的天体环境中肯定存在阳离子和被冰覆盖的谷物地幔。该报告最后讨论了如何将阳离子冰反应纳入星际云和原行星系统中分子形成和破坏的反应网络模型。