Malmir Masoume, Heravi Majid M, Yekke-Ghasemi Zahra, Mirzaei Masoud
Department of Chemistry, Faculty of Physics and Chemistry, Alzahra University, Vanak, PO Box 1993891176, Tehran, Iran.
Department of Chemistry, Faculty of Science, Ferdowsi University of Mashhad, Mashhad, 9177948974, Iran.
Sci Rep. 2022 Jul 7;12(1):11573. doi: 10.1038/s41598-022-15831-1.
Polyoxometalates (POMs) as efficient catalysts can be used a wide range of chemical transformations due to their tunable Brønsted/Lewis-acidity and redox properties. Herein, we reported two hybrid and heterogeneous lacunary Keggin catalysts: (TBA)[PWO] (TBA-PW) and (TBA)[SiWO]·4HO (TBA-SiW) (TBA: tetrabutylammonium) in which [XWO] anions were coated by TBA cations. In this form, TBA can easily trap reactants on the surface of the catalysts and increase the catalytic reaction. Therefore, the catalytic performance of both POMs was tested in cyanosilylation of numerous compounds bearing-carbonyl group and trimethylsilyl cyanide under solvent-free conditions. TBA-PW is more effective than TBA-SiW, conceivably due to the higher Lewis acidity of the P than the Si center and to the higher accessibility of the metal centers in the framework structure. Noteworthy, the recyclability and heterogeneity of both POMs catalysts were also examined, and the results confirmed that they remain active at least after three recycling procedures.
多金属氧酸盐（POMs）作为高效催化剂，因其可调节的布朗斯特/路易斯酸性和氧化还原性质，可用于广泛的化学转化反应。在此，我们报道了两种杂化非均相缺位Keggin催化剂：（TBA）[PWO]（TBA-PW）和（TBA）[SiWO]·4H₂O（TBA-SiW）（TBA：四丁基铵），其中[XWO]阴离子被TBA阳离子包覆。以这种形式，TBA能够轻松地将反应物捕获在催化剂表面并促进催化反应。因此，在无溶剂条件下，对这两种POMs在众多含羰基化合物与三甲基硅基氰的氰基硅烷化反应中的催化性能进行了测试。TBA-PW比TBA-SiW更有效，这可能是由于P中心比Si中心具有更高的路易斯酸性，以及骨架结构中金属中心具有更高的可及性。值得注意的是，还对这两种POMs催化剂的可回收性和非均相性进行了研究，结果证实它们至少在三次循环过程后仍保持活性。
