Direct quantitative identification of the "surface trans-effect".
Direct quantitative identification of the "surface trans-effect".
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DOI：
10.1039/c6sc01677d
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发表时间：
2016-09-01
期刊：
影响因子：
8.4
通讯作者：
Allegretti F
中科院分区：
文献类型：
--
作者：
Deimel PS;Bababrik RM;Wang B;Blowey PJ;Rochford LA;Thakur PK;Lee TL;Bocquet ML;Barth JV;Woodruff DP;Duncan DA;Allegretti F
表面反式效应的量化：离域表面，而不是原子，电子就像传统反式效应中的配体一样。经过多年的研究，已经建立了配位化学和金属表面吸附之间的强烈相似之处，分子和配体与金属表面内的单个原子形成局部键。最近提出的“表面反式效应”（STE）似乎是这种类似行为的进一步表现，但到目前为止，改性分子-金属表面键合的真实性质尚不清楚。STE可以在确定表面支撑的金属-有机配合物的反应性方面发挥重要作用，影响未来应用的系统设计。然而，目前对这种影响的理解是不完整的，缺乏可靠的结构参数，以基准理论计算。使用X射线驻波，我们证明，连接的氨和水的铁酞菁（FePc）在Ag（111）的中心铁原子的吸附高度增加，色散校正的密度泛函理论计算准确地模拟这种结构效应。吸附引起的FePc/H2O电子结构中的电荷重新分布的计算表明，电荷的积累沿着之间的表面，Fe原子和水分子的σ-键方向，类似于由氨引起的重新分布。在Ag（111）上观察到的STE的这种明显的σ-供体性质显示为涉及与离域金属表面电子的键合，而不是与一个或多个表面原子的局部键合，因此表明这是真正的表面反式效应。
Quantification of the surface trans-effect: delocalised surface, rather than atomic, electrons acting as if a ligand in a traditional trans-effect. The strong parallels between coordination chemistry and adsorption on metal surfaces, with molecules and ligands forming local bonds to individual atoms within a metal surface, have been established over many years of study. The recently proposed “surface trans-effect” (STE) appears to be a further manifestation of this analogous behaviour, but so far the true nature of the modified molecule–metal surface bonding has been unclear. The STE could play an important role in determining the reactivities of surface-supported metal–organic complexes, influencing the design of systems for future applications. However, the current understanding of this effect is incomplete and lacks reliable structural parameters with which to benchmark theoretical calculations. Using X-ray standing waves, we demonstrate that ligation of ammonia and water to iron phthalocyanine (FePc) on Ag(111) increases the adsorption height of the central Fe atom; dispersion corrected density functional theory calculations accurately model this structural effect. The calculated charge redistribution in the FePc/H2O electronic structure induced by adsorption shows an accumulation of charge along the σ-bonding direction between the surface, the Fe atom and the water molecule, similar to the redistribution caused by ammonia. This apparent σ-donor nature of the observed STE on Ag(111) is shown to involve bonding to the delocalised metal surface electrons rather than local bonding to one or more surface atoms, thus indicating that this is a true surface trans-effect.
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影响因子：
16.6
作者：
Gopakumar, Thiruvancheril G.;Matino, Francesca;Berndt, Richard
通讯作者：
Berndt, Richard
影响因子：
15
作者：
Flechtner, Ken;Kretschmann, Andreas;Gottfried, J. Michael
通讯作者：
Gottfried, J. Michael
影响因子：
4.4
作者：
BEHM, RJ;CHRISTMANN, K;VANHOVE, MA
通讯作者：
VANHOVE, MA
影响因子：
1.9
作者：
BATTEAS, JD;BARBIERI, A;SOMORJAI, GA
通讯作者：
SOMORJAI, GA
影响因子：
3.7
作者：
Bobaru, S. C.;Salomon, E.;Angot, T.
通讯作者：
Angot, T.