Synthesis and Characterization of Rhenium(V) Oxo Complexes Bearing PNP-Pincer Ligands

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• 作者：Ties J. Korstanje ; Martin Lutz ; Johann T. B. H. Jastrzebski ; Robertus J. M. Klein Gebbink
• 刊名：Organometallics
• 出版年：2014
• 出版时间：May 12, 2014
• 年：2014
• 卷：33
• 期：9
• 页码：2201-2209
• 全文大小：385K
• 年卷期：v.33,no.9(May 12, 2014)
• ISSN：1520-6041

文摘

The synthesis of a series of pyridine-based PNP-pincer rhenium-oxo complexes, with phenyl (1, 3), tert-butyl (2), or cyclohexyl (4) groups on the phosphorus atoms and either a ReO₂X (1, 2) or a ReCl₂O (3, 4) core is reported. The structures of these compounds were characterized using ¹H, ¹³C, and ³¹P NMR and using X-ray crystallography for 1 and 4. Compounds 2 and 3 crystallize as the corresponding ReO(OH)X compounds upon their reaction with moisture during the crystallization process. The complexes were tested as catalysts in the oxidation reaction of limonene with H₂O₂, the oxygen atom transfer reaction from pyridine N-oxide to triphenylphosphine, and the dehydration reaction of 1-phenylethanol, but all showed poor catalytic performance. All complexes can be deprotonated at the benzylic arm, and 2 can be deprotonated twice, accompanied by dearomatization of the pyridine ring. 3 and 4 are highly stable in their oxidized forms. The noninnocent behavior shown here could open up possibilities for cooperative catalysis.