Synthesis of Cyclopentadienyl-Based Tricarbonyl Rhenium Complexes and Some Unusual Reactivities of Cyclopentadienyl Substituents

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• 作者：Suresh Raju ; Christian A. M. R. van Slagmaat ; Martin Lutz ; Hendrik Kleijn ; Johann T. B. H. Jastrzebski ; Marc-Etienne Moret and Robertus J. M. Klein Gebbink
• 刊名：European Journal of Inorganic Chemistry
• 出版年：2017
• 出版时间：January 18, 2017
• 年：2017
• 卷：2017
• 期：3
• 页码：741-751
• 全文大小：1660K
• ISSN：1099-0682c

文摘

Cyclopentadienyl-based (Cp-based) tricarbonyl rhenium complexes [Cp&prime;Re(CO)b>3b>] are convenient precursors for the corresponding Cp-based trioxorhenium complexes (Cp&prime;ReOb>3b>), which are potential catalysts for the deoxydehydration (DODH) of diols to olefins. To evaluate the influence of different Cp substituents in Cp&prime;ReOb>3b> complexes in DODH, a series of alkyl-substituted Cp&prime;Re(CO)b>3b> complexes (<b>1ab>–<b>8ab>) were synthesized. High yields (86–98 %) were obtained from the reactions of Reb>2b>(CO)b>10b> with the corresponding Cp&prime;H ligands (<b>1b>–<b>8b>). The C–O infrared absorptions of <b>1ab>–<b>8ab> indicate that the electron-donating character of the Cp ligand increases with the number of substituents attached directly to the Cp ring. Analogous aryl-substituted complexes <b>10ab>–<b>12ab> containing bulky phenyl groups were accessed through the salt metathesis of ReBr(CO)b>5b> with the lithium salt of the deprotonated ligand (Cp&prime;Li), and the aryl groups decreased the electron donation. Furthermore, an unusual [6+4] cycloaddition reaction of (CpMeb>4b>H)Re(CO)b>3b> (<b>8ab>) with excess ligand resulted in the highly asymmetric Cp&prime;Re(CO)b>3b> complex <b>9ab>. Finally, the reaction of the tetraphenylcyclopentadienone ligand with Reb>2b>(CO)b>10b> was investigated and led to the isolation of two unusual compounds, namely, Re(CO)b>3b> complexes of the Shvo-type hydroxytetraphenylcyclopentadienyl ligand, [Phb>4b>Cp(OH)]Re(CO)b>3b> (<b>13ab>), and a benzofuran-fused cyclopentadienyl ligand, [Phb>3b>Cp(Cb>6b>Hb>4b>O)]Re(CO)b>3b> (<b>14ab>). X-ray crystal structures were obtained for the new Cp&prime;Re(CO)b>3b> complexes (CptBub>2b>Hb>3b>)Re(CO)b>3b> (<b>2ab>), [1,2,3-Meb>3b>(tetrahydroindenyl)]Re(CO)b>3b> (<b>7ab>), <b>9ab>, <b>13ab>, and <b>14ab>, which all have the typical three-legged “piano-stool&rdquo; configuration.