IONIZATION AND PROTONATION OF (MGCN) - AN AB-INITIO STUDY OF SOME GAS-PHASE PROPERTIES OF THE FIRST MAGNESIUM COMPOUND IN-SPACE
IONIZATION AND PROTONATION OF (MGCN) - AN AB-INITIO STUDY OF SOME GAS-PHASE PROPERTIES OF THE FIRST MAGNESIUM COMPOUND IN-SPACE
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DOI：
10.1016/0166-1280(94)04099-e
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发表时间：
1995-06-20
影响因子：
--
通讯作者：
LARGO, A
中科院分区：
文献类型：
--
作者：
BARRIENTOS, C;LARGO, A
用从头算方法研究了第一个由射电天文学家探测到的含镁分子--(MgCN)体系的电离和质子化衍生物。对于(MgCN)(+)体系，我们发现了一个循环基态，在相关的理论水平上，它分别比线性的MgCN+低1.8千卡摩尔(-1)和3.0千卡摩尔(-1)。估算的电离势较小，分别为7.93 eV和7.72 eV。质子化的最佳中心是碳和氮，其中镁碳和镁碳的质子亲和能都很高，均超过220千卡摩尔(-1)。还计算了在空间中可能产生(MgCN)前体的一些可能的离子-分子反应的热焓。结果表明，只有MgH+与异氰化氢反应生成(MgCN)(+)是明显的放热反应。
An ab initio study of the ionized and protonated derivatives of the (MgCN) system, the first magnesium-containing molecule detected by radioastronomers, has been carried out. For the (MgCN)(+) system we have found a cyclic ground state, lying below linear MgCN+ and MgNC+ by only 1.8 kcal mol(-1) and 3.0 kcal mol(-1), respectively, at correlated levels of theory. The estimated ionization potentials for both MgNC and MgCN are relatively small, 7.93 eV and 7.72 eV, respectively. The preferred protonation sites are carbon for MgNC and nitrogen for MgCN, with very high proton affinities of more than 220 kcal mol(-1) for both MgNC and MgCN. Enthalpies for some of the possible ion-molecule reactions which could produce precursors of (MgCN) in space have also been computed. It is found that only the reaction of MgH+ with hydrogen isocyanide to produce (MgCN)(+) is clearly exothermic.