Size-Dependent Polymorphism in Aluminum Carbide Cluster Anions AlnC2-: Formation of Acetylide-Containing Structures
Size-Dependent Polymorphism in Aluminum Carbide Cluster Anions AlnC2-: Formation of Acetylide-Containing Structures
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碳化铝簇阴离子 AlnC2- 的尺寸依赖性多态性：含乙酰化物结构的形成
DOI：
10.1021/acs.jpcc.7b12767
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
Tatsuya Tsukuda
中科院分区：
文献类型：
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作者：
Kazuyuki Tsuruoka;Kiichirou Koyasu ;Shinichi Hirabayashi;Masahiko Ichihashi;Tatsuya Tsukuda
在激光烧蚀铝与甲醇、乙醇、戊烷、乙腈、丙酮等有机分子气相反应中，碳化铝簇阴离子AlnC2 - (n= 5 ~ 13)是最主要的产物。密度泛函理论计算预测了AlnC2 -的两种可能的异构体结构：一种是两个碳解离的异构体（D型），如块状碳化铝；另一种是两个碳形成类似乙酰基的c2单元的新型异构体。后一种异构体根据C2unit的位置进一步分为三种类型：C2unit被封装在Al笼内（I型），包含在Al簇的表面（S型），或附着在Al簇的表面（O型）。光电子能谱测定的alnc2的绝热电子亲和的大小依赖行为用多态性作为大小(n)的函数来解释：I型型= 5-8，D型= 9-11，D型或O型= 12，O型= 13。C2unit的位置随着in的增加而由内向外移动的趋势归因于形成Al-C键和Al-Al键所获得的稳定之间的平衡。较小的alnc2 -簇（n= 5-8）倾向于用Al原子包围类似乙酰基的c2单元，以最大化Al - c键的数量，而较大的alnc2 -簇（n= 12和13）倾向于将c2单元附着在Al簇的表面，以最大化Al - Al键的数量。
Aluminum carbide cluster anions AlnC2–(n= 5–13) were observed as the most dominant products in the gas-phase reactions of laser-ablated Aln–with organic molecules, such as methanol, ethanol, pentane, acetonitrile, or acetone. Density functional theory calculations predicted two possible isomeric structures for AlnC2–: isomers in which two carbons are dissociated (type D) as in the case of the bulk aluminum carbide and novel isomers in which two carbons form an acetylide-like C2unit. The latter isomers are further categorized into three types depending on the location of the C2unit: the C2unit is encapsulated within the Al cage (type I), contained in the surface of Al clusters (type S), or attached to the surface of Al clusters (type O). Size-dependent behavior of the adiabatic electron affinities of AlnC2determined by photoelectron spectroscopy was explained in terms of polymorphism as a function of size (n): type I forn= 5–8, type D forn= 9–11, type D or O forn= 12, and type O forn= 13. The tendency in which the position of the C2unit was shifted from the inside to outside with the increase innwas ascribed to the balance between the stabilizations gained by forming Al–C bonds and Al–Al bonds. The smaller AlnC2–clusters (n= 5–8) prefer to surround the acetylide-like C2unit with the Al atoms so as to maximize the number of Al–C bonds, whereas larger ones (n= 12 and 13) prefer to attach the C2unit onto the surface of the Al clusters so as to maximize the number of Al–Al bonds.