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首页> 外文期刊>Organometallics >Role of the ligand and of the size and flexibility of the palladium-ancillary ligand cycle on the reactivity of substituted alkynes toward palladium(0) complexes bearing potentially terdentate nitrogen-sulfur-nitrogen or nitrogen-nitrogen-nitrogen li
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Role of the ligand and of the size and flexibility of the palladium-ancillary ligand cycle on the reactivity of substituted alkynes toward palladium(0) complexes bearing potentially terdentate nitrogen-sulfur-nitrogen or nitrogen-nitrogen-nitrogen li

机译：配体的作用以及钯-辅助配体循环的大小和柔韧性对取代炔烃对带有潜在齿状氮-硫-氮或氮-氮-氮锂的钯（0）配合物的反应性的作用

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摘要

The reaction between palladium( 0) complexes bearing potentially terdentate ligands and dimethyl acetylenedicarboxylate (DMA) to give the corresponding palladacyclopentadiene complexes was studied under kinetic conditions. The reactivity of the complexes was markedly influenced by the nature of the ancillary ligand. Thus, when pyridyldithioether (SNS) and dipyridylthioether (NSN) ligands are used, the reactivity and the rate law of the corresponding derivatives are similar to those of the unsubstituted bidentate pyridylthioether substrates and, therefore, a marked rate increase can be obtained only by reduction of the olefin steric requirement. When terdentate NNN ligands are used, an apparent difference in reactivity between the derivatives bearing the pyridine- amine-pyridine and pyridine-amine-quinoline ligands is observed. On the basis of a detailed structural study (NMR, X-ray) and on kinetic investigations, an interpretation which takes into account the flexibility of the cycle formed between the ligand and palladium is proposed. Thus, irrespective of the size of the cycle, the complexes in which the ligand forms flexible cycles undergo ring opening less easily, with a consequent reduction of reactivity. Conversely, rigid rings cannot undergo associative attack without companion ring opening, this phenomenon being crucial in favoring the alkyne attack.
机译：在动力学条件下研究了带有潜在的齿状配体的钯（0）配合物与乙炔二羧酸二甲酯（DMA）之间的反应，得到了相应的钯环戊二烯配合物。复合物的反应性明显受辅助配体的性质影响。因此，当使用吡啶基二硫醚（SNS）和二吡啶基硫醚（NSN）配体时，相应衍生物的反应性和速率定律与未取代的二齿吡啶基硫醚底物相似，因此，只有通过还原才能获得显着的速率增加。烯烃空间要求。当使用齿状NNN配体时，在带有吡啶-胺-吡啶配体和吡啶-胺-喹啉配体的衍生物之间观察到反应性的明显差异。在详细的结构研究（NMR，X射线）和动力学研究的基础上，提出了一种解释，该解释考虑了配体和钯之间形成的循环的灵活性。因此，不管循环的大小如何，其中配体形成挠性循环的络合物较不容易开环，从而降低了反应性。相反，刚性环在没有伴侣环打开的情况下不能进行联合攻击，这种现象对于促进炔烃攻击至关重要。

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