Well-Defined Surface Species [(≡Si - O -)W(=O)Me3] Prepared by Direct Methylation of [(≡Si - O -)W(=O)Cl3], a Catalyst for Cycloalkane Metathesis and Transformation of Ethylene to Propylene
AuthorsHamieh, Ali Imad Ali
Goh, Li Min Serena
KAUST DepartmentAli I. Al-Naimi Petroleum Engineering Research Center (ANPERC)
Chemical Science Program
KAUST Catalysis Center (KCC)
KAUST Solar Center (KSC)
Physical Science and Engineering (PSE) Division
Online Publication Date2015-03-04
Print Publication Date2015-04-03
Permanent link to this recordhttp://hdl.handle.net/10754/564137
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AbstractThe silica-supported tungsten oxo-trimethyl complex [(≡Si - O -)W(=O)Me3] was synthesized using a novel SOMC synthetic approach. By grafting the inexpensive stable compound WOCl4 on the surface of silica, partially dehydroxylated at 700 °C (SiO2-700), a well-defined monopodal surface complex [(≡Si - O -)W(=O)Cl3] was produced. The supported complex directly methylated with ZnMe2 and transformed into [(≡Si - O -)W(=O)Me3], which we fully characterized by microanalysis, IR, mass balance and SS NMR (1H, 13C, 1H-13C HETCOR, 1H-1H DQ and TQ). [(≡Si - O)W(=O)Me3] has two conformational isomers on the surface at room temperature. The conversion of one to the other was observed at 318 K by variable-temperature 13C CP/MAS and 1H spin echo MAS solid-state NMR; this was also confirmed by NMR and DFT calculations. [(≡Si - O)W(=O)Me3] was found to be active in cyclooctane metathesis and to have a wide distribution range in ring-contracted and ring-expanded products. In addition, [(≡Si - O)W(=O)Me3] proved to be highly active for selective transformation of ethylene to propylene compared to other silica-supported organometallic complexes. (Chemical Equation Presented). © 2015 American Chemical Society.
SponsorsThis work was supported by funds from King Abdullah University of Science and Technology (KAUST).
PublisherAmerican Chemical Society (ACS)