Abstract
Reactions of [VCl3(thf)3] or VBr3 with 2,2′-bipyridine (bpy) or 1,10-phenanthroline (phen) in a 1:1 molar ratio in air under solventothermal conditions has afforded polymeric oxidovanadium(IV) four complexes 1–4 of a general formula [VO(L)X2]n (L = bpy, phen and X = Cl, Br). Monomeric complex [VO(DMF)(phen)Br2] (4a) has been obtained by the treatment of compound 4 with DMF. The complexes were characterized by IR spectroscopy and elemental analysis. The crystal structures of 3 and 4a were determined by an X-ray diffraction (XRD) analysis. The {VOBr2(bpy)} fragments in 3 form infinite chains due to the V = O…V interactions. The vanadium atom has a distorted octahedral coordination environment. Complexes 1–4 have been tested as catalysts in the homogeneous oxidation of alkanes (to produce corresponding alkyl hydroperoxides which can be easily reduced to alcohols by PPh3) and alcohols (to corresponding ketones) with H2O2 or tert-butyl hydroperoxide in MeCN. Compound 1 exhibited the highest activity. The mechanism of alkane oxidation was established using experimental selectivity and kinetic data and theoretical DFT calculations. The mechanism is of the Fenton type involving the generation of HO• radicals.
Highlights
Many organic reactions catalyzed by metal complexes have been reported in the recent years.Organic and inorganic peroxides and especially hydrogen peroxide are widely employed for the oxidationCatalysts 2019, 9, 217; doi:10.3390/catal9030217 www.mdpi.com/journal/catalystsCatalysts 2019, 9, 217 of various organic compounds
We have reported the synthesis of monomeric square-pyramidal oxidovanadium(IV)
Solventothermal conditions were applied for the synthesis of oxidovanadium(IV) complexes
Summary
Many organic reactions catalyzed by metal complexes have been reported in the recent years. The reactions of alkanes (as well as alcohols containing C–H bonds) occur with the intermediate formation of free O- and C-centered radicals. In 1993, Shul’pin and coworkers discovered a highly efficient system for the oxidation of hydrocarbons consisting of the combination of a vanadate anion and pyrazine-2-carboxylic acid [40,41] Later, this system, which catalyzes the transformation of alkanes into corresponding alkyl hydroperoxides with hydrogen peroxide in an acetonitrile solution, was investigated in detail [42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62].
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
