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首页> 外文期刊>Chemistry: A European journal >On the Critical Effect of the Metal (Mo vs. W) on the [3+2] Cycloaddition Reaction of M3S4 Clusters with Alkynes: Insights from Experiment and Theory
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On the Critical Effect of the Metal (Mo vs. W) on the [3+2] Cycloaddition Reaction of M3S4 Clusters with Alkynes: Insights from Experiment and Theory

机译：金属（Mo与W）对带有炔烃的M3S4团簇[3 + 2]环加成反应的临界效应：实验和理论的启示

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Whereas the cluster [Mo3S4(acac)(3)(py)(3)](+) ([1](+), acac=acetylacetonate, py=pyridine) reacts with a variety of alkynes, the cluster [W3S4(acac)(3)(py)(3)](+) ([2](+)) remains unaffected under the same conditions. The reactions of cluster [1]+ show polyphasic kinetics, and in all cases clusters bearing a bridging dithiolene moiety are formed in the first step through the concerted [3+2] cycloaddition between the C equivalent to C atoms of the alkyne and a Mo(mu-S)(2) moiety of the cluster. A computational study has been conducted to analyze the effect of the metal on these concerted [3+ 2] cycloaddition reactions. The calculations suggest that the reactions of cluster [2](+) with alkynes feature Delta G(+) values only slightly larger than its molybdenum analogue, however, the differences in the reaction free energies between both metal clusters and the same alkyne reach up to approximately 10 kcal mol(-1), therefore indicating that the differences in the reactivity are essentially thermodynamic. The activation strain model (ASM) has been used to get more insights into the critical effect of the metal center in these cycloadditions, and the results reveal that the change in reactivity is entirely explained on the basis of the differences in the interaction energies E-int between the cluster and the alkyne. Further decomposition of the E-int values through the localized molecular orbital-energy decomposition analysis (LMO-EDA) indicates that substitution of the Mo atoms in cluster [1](+) by W induces changes in the electronic structure of the cluster that result in weaker intra-and inter-fragment orbital interactions.
机译：簇[Mo3S4（acac）（3）（py）（3）]（+）（[1]（+），acac =乙酰丙酮酸酯，py =吡啶）与各种炔烃反应，而簇[W3S4（acac） ）（3）（py）（3）]（+）（[2]（+））在相同条件下不受影响。团簇[1] +的反应显示了多相动力学，在所有情况下，第一步都是通过炔烃的C原子碳原子与Mo的[3 + 2]环加成环合形成带有桥联二硫烯基团的团簇簇的（mu-S）（2）部分。已经进行了计算研究，以分析金属对这些协同的[3 + 2]环加成反应的影响。计算表明，簇[2]（+）与炔烃的反应特征在于δG（+）值仅比其钼类似物稍大，但是，两个金属簇与同一炔烃之间的反应自由能的差异达到了大约为10 kcal mol（-1），因此表明反应性的差异本质上是热力学的。活化应变模型（ASM）已被用于深入了解金属中心在这些环加成反应中的关键作用，结果表明，反应性的变化是完全根据相互作用能E-的差异来解释的。集群和炔烃之间的整数。通过局部分子轨道能量分解分析（LMO-EDA）对E-int值的进一步分解表明，簇[1]（+）中的Mo原子被W取代会引起簇的电子结构发生变化在较弱的碎片内部和碎片间轨道相互作用中。

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