title: Chloride-bridged oxovanadium(V) complexes with alkoxyalkoxide ligands. Synthesis, structure, electrochemistry and reactivities.
abstract: A series of mixed alkoxyalkoxo chloro complexes of vanadium(V), [VOCl2(OCH2CH2OR)]2 (R = Me, Et, iPr, Bz), [VOCl2(OCMe2CH2OMe)]2 and [VOCl2(OCH2(cyclo-C4H7O)]2, were synthesised and characterised. The title compounds can be obtained either from VOCl3 and the alkoxyalcohols by HCl elimination or from the corresponding lithium alkoxides and VOCl3 by salt metathesis reaction. X-Ray diffraction studies revealed the title compounds to be dimers with chloride bridging ligands and intramolecular ether coordination. Electrochemical results obtained by cyclic voltammetry indicate irreversible, reductive behaviour. The interactions of the title compounds with oxygen, nitrogen and phosphorus donor ligands were examined. Phosphorus and nitrogen donors lead to reduction products whereas tetrahydrofuran coordinates to the vanadium(V) centre by breaking the chloride bridge. All tetrahydrofuran complexes, [VOCl2(OCH2CH2OR)(thf)] (R = Me, Et, iPr) and [VOCl2(OCMe2CH2OMe)(thf)], have been characterised by single-crystal X-ray diffraction. The solid-state structures of these complexes show that they consist of six-coordinate monomers. Reaction of [VOCl2(OCH2CH(2)OMe)]2 with Me3SiCH2MgCl gave [VO(CH2SiMe3)3], which has been structurally characterised. The compounds were tested as catalysts for epoxidation and polymerisation reactions. They convert unfunctionalised olefins into the corresponding epoxides with moderate activity. They are good pre-catalysts for the polymerisation of ethene and oligomerise 1-hexene.
authors.affiliation: Institut für Chemie, Technische Universität Berlin, Germany. Esther.Rosenthal@tu-berlin.de
authors.forename: Esther C E
authors.initials: EC
authors.lastname: Rosenthal
authors.forename: Huiling
authors.initials: H
authors.lastname: Cui
authors.forename: Juliane
authors.initials: J
authors.lastname: Koch
authors.forename: Petra
authors.initials: P
authors.lastname: Escarpa Gaede
authors.forename: Markus
authors.initials: M
authors.lastname: Hummert
authors.forename: Sebastian
authors.initials: S
authors.lastname: Dechert
mesh_terms: D002384:Catalysis; D002712:Chlorides / Q000737:chemistry*; D018360:Crystallography, X-Ray; D004563:Electrochemistry; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry; D010087:Oxides / Q000737:chemistry*; D014639:Vanadium / Q000737:chemistry*
chemical_list: D002712:Chlorides; D008024:Ligands; D009942:Organometallic Compounds; D010087:Oxides; D014639:Vanadium