Miyajima Ken, Fukushima Naoya, Mafuné Fumitaka
J Phys Chem A. 2009 Apr 30;113(17):4858-61. doi: 10.1021/jp901963d.
Bielement metal clusters composed of the group 5 elements, A(n)B(m) (A, B = V, Nb, Ta), were prepared in the gas phase over the wide n and m ranges. We measured reactivities of the attachment reaction of the neutral clusters to H(2), which were plotted as a function of a map with n and m. The clusters with n + m = 4 and 5 were found to be more reactive than the other clusters. The measurement of the ionization energies reveals that there is no strong correlation between the reactivity and the ionization energy. In addition, the reactivities of the cations, A(n)B(m)(+), were also highest at n + m = 4 and 5. These findings suggest that the electronic structure does not totally determine the reactivity of the neutral clusters. On the other hand, theoretical calculations for A(n)B(m) (n + m = 4) reported by Metha et al. showed that the optimized geometrical structures of the congener group 5 bielement clusters do not change significantly by changing n and m within n + m = 4. Hence, it is highly likely that the pyramidal (n + m = 4) and bipyramidal (n + m = 5) structures of A(n)B(m) determine the high reactivity of the clusters.
由第5族元素组成的双元素金属簇A(n)B(m)（A、B = V、Nb、Ta）在气相中于较宽的n和m范围内制备而成。我们测量了中性簇与H₂的附着反应活性，并将其绘制为n和m的函数图。发现n + m = 4和5的簇比其他簇更具反应活性。电离能的测量结果表明，反应活性与电离能之间没有很强的相关性。此外，阳离子A(n)B(m)(+)的反应活性在n + m = 4和5时也最高。这些发现表明，电子结构并不能完全决定中性簇的反应活性。另一方面，梅塔等人报道的A(n)B(m)（n + m = 4）的理论计算表明，在n + m = 4范围内改变n和m时，同属第5族的双元素簇的优化几何结构变化不大。因此，A(n)B(m)的金字塔形（n + m = 4）和双金字塔形（n + m = 5）结构很可能决定了簇的高反应活性。
