Please use this identifier to cite or link to this item:
http://hdl.handle.net/10773/26353
Title: | A comparative study of molybdenum carbonyl and oxomolybdenum derivatives bearing 1,2,3-triazole or 1,2,4-triazole in catalytic olefin epoxidation |
Author: | Nogueira, Lucie S Neves, Patrícia Gomes, Ana C. Amarante, Tatiana A Almeida Paz, Filipe A. Valente, Anabela A. Gonçalves, Isabel S. Pillinger, Martyn |
Keywords: | Molybdenum Triazole Carbonyl complexes Oxidative decarbonylation Epoxidation |
Issue Date: | 28-Dec-2018 |
Publisher: | MDPI |
Abstract: | The molybdenum(0)-carbonyl-triazole complexes [Mo(CO)₃(L)₃] [L = 1,2,3-triazole (1,2,3-trz) or 1,2,4-triazole (1,2,4-trz)] have been prepared and examined as precursors to molybdenum(VI) oxide catalysts for the epoxidation of cis-cyclooctene. Reaction of the carbonyl complexes with the oxidant tert-butyl hydroperoxide (TBHP) (either separately or in situ) gives oxomolybdenum(VI) hybrid materials that are proposed to possess one-dimensional polymeric structures in which adjacent oxo-bridged dioxomolybdenum(VI) moieties are further linked by bidentate bridging triazole (trz) ligands. A pronounced ligand influence on catalytic performance was found and the best result (quantitative epoxide yield within 1 h at 70 °C) was obtained with the 1,2,3-triazole oxomolybdenum(VI) hybrid. Both molybdenum oxide-triazole compounds displayed superior catalytic performance in comparison with the known hybrid materials [MoO₃(trz)0.5], which have different structures based on organic-inorganic perovskite-like layers. With aqueous H₂O₂ as the oxidant instead of TBHP, all compounds were completely soluble and active. A pronounced ligand influence on catalytic performance was only found for the hybrids [MoO₃(trz)0.5], and only the 1,2,4-trz compound displayed reaction-induced self-precipitation behavior. An insight into the type of solution species that may be involved in the catalytic processes with these compounds was obtained by separately treating [MoO₃(1,2,4-trz)0.5] with excess H₂O₂, which led to the crystallization of the complex (NH₄)1.8(H₃O)0.2[Mo₂O₂(μ₂-O)(O₂)₄(1,2,4-trz)]·H₂O. The single-crystal X-ray investigation of this complex reveals an oxo-bridged dinuclear structure with oxodiperoxo groups being further linked by a single triazole bridge. |
Peer review: | yes |
URI: | http://hdl.handle.net/10773/26353 |
DOI: | 10.3390/molecules24010105 |
ISSN: | 1420-3049 |
Publisher Version: | https://www.mdpi.com/1420-3049/24/1/105 |
Appears in Collections: | CICECO - Artigos |
Files in This Item:
File | Description | Size | Format | |
---|---|---|---|---|
molecules-24-00105-v3.pdf | 1.91 MB | Adobe PDF | View/Open |
Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.