Departamento de Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica, Facultad de Ciencias, Universidad de Cádiz , Apartado 40, Puerto Real, 11510 Cádiz, Spain.
Inorg Chem. 2013 Dec 16;52(24):14334-42. doi: 10.1021/ic4023344. Epub 2013 Nov 22.
Reaction of [Mo3(μ3-S)(μ-S)3] clusters with alkynes usually leads to formation of two C-S bonds between the alkyne and two of the bridging sulfides. The resulting compounds contain a bridging alkenedithiolate ligand, and the metal centers appear to play a passive role despite reactions at those sites being well illustrated for this kind of cluster. A detailed study including kinetic measurements and DFT calculations has been carried out to understand the mechanism of reaction of the Mo3(μ3-S)(μ-S)3(H2O)9 (1) cluster with two different alkynes, 2-butyne-1,4-diol and acetylenedicarboxylic acid. Stopped-flow experiments indicate that the reaction involves the appearance in a single kinetic step of a band at 855 or 875 nm, depending on the alkyne used, a position typical of clusters with two C-S bonds. The effects of the concentrations of the reagents, the acidity, and the reaction medium on the rate of reaction have been analyzed. DFT and TD-DFT calculations provide information on the nature of the product formed, its electronic spectrum and the energy profile for the reaction. The structure of the transition state indicates that the alkyne approaches the cluster in a lateral way and both C-S bonds are formed simultaneously.
[Mo3(μ3-S)(μ-S)3] 簇与炔烃的反应通常导致炔烃和两个桥接硫之间形成两个 C-S 键。所得化合物含有桥接烯二硫醇配体，尽管此类簇合物的这些位点的反应得到了很好的说明，但金属中心似乎发挥了被动作用。已经进行了详细的研究，包括动力学测量和 DFT 计算，以了解 Mo3(μ3-S)(μ-S)3(H2O)9 (1) 簇与两种不同炔烃，2-丁炔-1,4-二醇和丙炔二酸的反应机理。停流实验表明，反应涉及在单个动力学步骤中出现 855 或 875nm 的带，具体取决于所用的炔烃，这是具有两个 C-S 键的簇的典型位置。已经分析了试剂浓度、酸度和反应介质对反应速率的影响。DFT 和 TD-DFT 计算提供了有关形成的产物的性质、其电子光谱和反应能量曲线的信息。过渡态的结构表明，炔烃以横向方式接近簇，并且同时形成两个 C-S 键。
