SOMC grafting of vanadium oxytriisopropoxide (VO(OiPr)3) on dehydroxylated silica; analysis of surface complexes and thermal restructuring mechanism
AuthorsHögerl, Manuel P.
Serena Goh, Li Min
Pasha, Farhan Ahmad
KAUST DepartmentKAUST Catalysis Center (KCC)
Permanent link to this recordhttp://hdl.handle.net/10754/628452
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AbstractVanadium oxytriisopropoxide (VO(OPr)), 1, was grafted on highly dehydroxylated silica (SiO: aerosil silica treated at 700 °C under high vacuum) to generate compound 2 following the concepts and methodology of surface organometallic chemistry (SOMC). The resulting compound was analyzed by elemental analysis, FT-IR, H, C and V solid state (SS) NMR, Raman and EPR spectroscopies. The grafting reaction of 1 to generate 2 was found to lead to the formation of a monopodal surface complex [(Si-O-)V(O)(OPr)], 2m, as well as bipodal [(Si-O-)V(O)(OPr)], 2b, formed along with (Si-O-Pr) moieties as an effect of the classical rearrangement of 2m with strained siloxane bridges. Upon controlled thermal treatment at 200 °C under high vacuum, 2m and 2b were found to mainly rearrange to tetrahedral VO moieties [(Si-O-)V(O)] (3) with formation of propylene whereas the (Si-O-Pr) groups were preserved. The mechanism of the thermal rearrangement of the isopropoxide groups was investigated by a DFT approach revealing the occurrence of a concerted γ-H-transfer and olefin elimination mechanism.
CitationHögerl MP, Serena Goh LM, Abou-Hamad E, Barman S, Dachwald O, et al. (2018) SOMC grafting of vanadium oxytriisopropoxide (VO(OiPr)3) on dehydroxylated silica; analysis of surface complexes and thermal restructuring mechanism. RSC Advances 8: 20801–20808. Available: http://dx.doi.org/10.1039/c8ra02419g.
SponsorsThis work was funded by King Abdullah University of Science and Technology, Thuwal, Saudi Arabia. The authors declare no competing financial interest. V. D. E. thanks the Thailand Research Fund (Grant No. RSA6080059) for funding this research.
PublisherRoyal Society of Chemistry (RSC)
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