Facile and Efficient Synthesis of the Surface Tantalum Hydride (鈮iO)2TaIIIH and Tris-Siloxy Tantalum (鈮iO)3TaIII Starting from Novel Tantalum Surface Spec

详细信息    查看全文

• 作者：Yin Chen ; Samy Ould-Chikh ; Edy Abou-Hamad ; Emmanuel Callens ; Janet C. Mohandas ; Syed Khalid ; Jean-Marie Basset
• 刊名：Organometallics
• 出版年：2014
• 出版时间：March 10, 2014
• 年：2014
• 卷：33
• 期：5
• 页码：1205-1211
• 全文大小：372K
• 年卷期：v.33,no.5(March 10, 2014)
• ISSN：1520-6041

文摘

By grafting of TaMe₅ (1) on the surface of silica partially dehydroxylated at 500 掳C (silica₅₀₀), a mixture of (鈮iO)TaMe₄ (2a; major, 65 卤 5%) and (鈮iO)₂TaMe₃ (2b; minor, 35 卤 5%) was produced, which has been characterized by microanalysis, IR, and SS NMR (¹H, ¹³C, ¹H鈥?sup>13C HETCOR, proton double and triple quantum). After grafting, these surface organometallic compounds are more stable than the precursor TaMe₅. Treatment of 2a,b with water and H₂ resulted in the formation of methane in amount of 3.6 卤 0.2 and 3.4 卤 0.2 mol/grafted Ta, respectively. 2a,b react with H₂ (800 mbar) to form (鈮iO)₂TaH. After (鈮iO)₂TaH was heated to 500 掳C under hydrogen or vacuum, [(鈮iO)₃Ta][鈮iH] was produced, and the structure was confirmed by IR, NMR, and EXAFS. Considering the difficulty of the previous preparation method, these syntheses represent a facile and convenient way to prepare tantalum surface species (鈮iO)₂TaH and (鈮iO)₃Ta via the intermediate of the new surface organometallic precursors: (鈮iO)TaMe₄/(鈮iO)₂TaMe₃. (鈮iO)₂TaH and (鈮iO)₃Ta exhibit equal reactivities in alkane metathesis and ethylene polymerization in comparison to those in previous reports.