Indiana University, Department of Chemistry, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, USA.
J Chem Phys. 2011 Sep 14;135(10):104312. doi: 10.1063/1.3635408.
Anion photoelectron spectra of Mo(3)O(y)(-) and W(3)O(y)(-) (y = 3-6) are reported and analyzed using density functional theory results in an attempt to determine whether electronic and structural trends in the less oxidized clusters (y = 3, 4) could elucidate the disparate chemical properties of the M(3)O(y)(-) (M = Mo, W, y = 5, 6) species. In general, cyclic structures are calculated to be more stable by at least 1 eV than extended structures, and the lowest energy structures calculated for the most reduced species favor M = O terminal bonds. While the numerous low-energy structures found for Mo(3)O(y)(-)/Mo(3)O(y) and W(3)O(y)(-)/W(3)O(y) were, in general, similar, various structures of W(3)O(y)(-)/W(3)O(y) were found to be energetically closer lying than analogous structures of Mo(3)O(y)(-)/Mo(3)O(y). Additionally, the Mo-O-Mo bridge bond was found to be a more stabilizing structural motif than the W-O-W bridge bond, with the oxygen center in the former having the highest negative charge. Based on this, the observation of trapped intermediates in reactions between Mo(3)O(y)(-) and water or CO(2) that are not observed in analogous W(3)O(y)(-) reactivity studies may be partially attributed to the role of bridge bond fluxionality.
报道并分析了 Mo(3)O(y)(-) 和 W(3)O(y)(-)（y = 3-6）的负离子光电子能谱，使用密度泛函理论结果来尝试确定氧化程度较低的团簇（y = 3、4）中的电子和结构趋势是否可以阐明 M(3)O(y)(-)（M = Mo、W、y = 5、6）物种的不同化学性质。通常，环状结构比伸展结构稳定至少 1 eV，对于最还原的物种，计算出的最低能量结构有利于 M = O 端键。虽然为 Mo(3)O(y)(-) / Mo(3)O(y) 和 W(3)O(y)(-) / W(3)O(y) 找到的许多低能量结构在一般情况下是相似的，但 W(3)O(y)(-) / W(3)O(y) 的各种结构比 Mo(3)O(y)(-) / Mo(3)O(y) 的类似结构在能量上更接近。此外，Mo-O-Mo 桥键被发现是比 W-O-W 桥键更稳定的结构基序，前一种结构中氧中心的负电荷最高。基于此，Mo(3)O(y)(-) 与水或 CO(2) 之间反应中观察到的中间体被捕获，而在类似的 W(3)O(y)(-) 反应性研究中则没有观察到，这可能部分归因于桥键流变性的作用。
