Dioxotungsten(vi) complexes with isoniazid-related hydrazones as (pre)catalysts for olefin epoxidation: solvent and ligand substituent effects. Issue 43 (13th April 2016)

• Record Type: Journal Article
• Authors: Vrdoljak, Višnja; Pisk, Jana; Prugovečki, Biserka; Agustin, Dominique; Novak, Predrag; Matković-Čalogović, Dubravka
• Is Part Of: RSC advances. Volume 6:Issue 43(2016)
• Page Start: 36384
• Page End: 36393
• Publication Date: 2016-04-13
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c6ra05067k
• Languages: English
• ISSNs: 2046-2069

Abstract

Abstract : The catalytic performances (activity and selectivity) of the mononuclear dioxotungsten(vi ) complexes [WO2 (L R )(D)] towards alkene epoxidation by tert -butyl hydroperoxide (TBHP) were investigated under different conditions. Abstract : The mononuclear dioxotungsten(vi ) complexes [WO2 (L 3OMe )(D)] (1a and1b ), [WO2 (L 4OMe )(D)] (2a and2b ) and [WO2 (L H )(D)] (3a and3b ) (D = EtOH (1a–3a ) or MeOH (1b–3b ); L 3OMe = 3-methoxy-2-oxybenzaldehyde isonicotinoyl hydrazonato, L 4OMe = 4-methoxy-2-oxybenzaldehyde isonicotinoyl hydrazonato, L H = 2-oxybenzaldehyde isonicotinoyl hydrazonato) were synthesized by the reaction of [WO2 (acac)2 ]·0.5C6 H5 Me with the respective isoniazid-related hydrazone. The compounds were characterized by microanalysis, FT-IR and NMR spectroscopy, thermogravimetric analysis, and powder X-ray diffraction method. The crystal and molecular structures of1a, 1b, 3a and [WO2 (acac)2 ]·0.5C6 H5 Me were determined by single crystal X-ray diffraction. The structures of1a, 1b, 3a are mononuclear and form hydrogen bonded centrosymmetric dimers. In all three complexes, the dimers are also held together by π⋯π interactions between aromatic rings. The catalytic performances (activity and selectivity) of1a–3a and1b–3b towards alkene epoxidation by tert -butyl hydroperoxide (TBHP) were investigated under different conditions.