To What Extent Do Iodomethane and Bromomethane Undergo Analogous Reactions?
To What Extent Do Iodomethane and Bromomethane Undergo Analogous Reactions?
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DOI：
10.1021/acs.jpca.3c08337
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发表时间：
2024-02
期刊：
影响因子：
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通讯作者：
Haiming Wu;Y. Jia;Xiaoyun Zhao;Lijun Geng;Shiquan Lin;Si-Dian Li;Zhixun Luo
中科院分区：
文献类型：
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作者：
Haiming Wu;Y. Jia;Xiaoyun Zhao;Lijun Geng;Shiquan Lin;Si-Dian Li;Zhixun Luo
碘甲烷和溴甲烷（CH 3 I/CH 3Br）是常见的化学物质，但它们在纳米金属上的化学性质尚未完全了解。本文分析了Rhn+（n = 3-30）团簇与卤代甲烷的反应性，揭示了C-H键和C-X键活化的自旋效应和浓度依赖性。发现富卤甲烷条件下的反应不同于富金属条件下的反应。在少量反应物存在下，CH 3 I和CH 3Br在Rhn+簇上发生类似的脱氢反应;然而，在足够的CH 3 I/CH 3Br存在下，观察到不同的反应，显示出主要的Rh（CH 3Br）x+（x = 1-4）产物，但一系列RhnCxHyIz+物种（x = 1-4，y = 1-12，z = 1-5）与H2，HI或CH 4的去除有关。密度泛函理论计算表明，CH 3Br的脱氢和脱甲烷反应放热相对较少，如果氦气冷却立即带走能量，则会被足够的气体碰撞所钝化;相反，CH 3Br的连续吸附会产生一系列Rh（CH 3Br）x+物种，并伴随着C-Br键的意外解离.
Iodomethane and bromomethane (CH3I/CH3Br) are common chemicals, but their chemistry on nanometals is not fully understood. Here, we analyze the reactivity of Rhn+ (n = 3-30) clusters with halomethanes and unveil the spin effect and concentration dependence in the C-H and C-X bond activation. It is found that the reactions under halomethane-rich conditions differ from those under metal-rich conditions. Both CH3I and CH3Br undergo similar dehydrogenation on the Rhn+ clusters in the presence of small quantity reactants; however, different reactions are observed in the presence of sufficient CH3I/CH3Br, showing dominant Rh(CH3Br)x+ (x = 1-4) products but a series of RhnCxHyIz+ species (x = 1-4, y = 1-12, and z = 1-5) pertaining to H2, HI, or CH4 removal. Density functional theory calculations reveal that the dehydrogenation and demethanation of CH3Br are relatively less exothermic and will be deactivated by sufficient gas collisions if helium cooling takes away energy immediately; instead, the successive adsorption of CH3Br gives rise to a series of Rh(CH3Br)x+ species with accidental C-Br bond dissociation.