Monomere und dimere Oxovanadium(IV)-phenolate: Synthese,Struktur und Reaktionen mit reduzierenden und arylierenden Reagenzien

Monomeric and Dimeric Oxovanadium(IV)-phenolate Complexes: Synthesis, Structure, and Reaction with a Reducing and Arylation Agent Reaction of [OVCl₂(THF)₂] with LiOMes yields dimeric [Li(Et₂O)₂OVCl₂(μ-OMes)]₂ ( 1 ) which can be converted with excess LiOMes to the substitution product [Li(THF)₂OV(OMes)₃(THF)] ( 2 ). Treatment of ( 1 ) with LiMes results in the formation of complexes [Li(THF)₃OVMes₃] ( 3 ) and [Li(THF)₃OVMes₂(OMes)] ( 4 ). Complex [{Li(THF)₂OV(OMes)₂(μ-OH)}₂ · 2 THF] ( 6 ) has been isolated as a by-product of an unknown reaction of [OV(OMes)₃] and Li. The structures of 1 , 2 , 3 , and 6 have been determined by X-ray analysis. In 1 (monoclinic, P2₁/c, a = 9.522(1) Å, b = 19.777(2) Å, c = 12.311(1) Å, β = 104.45(1)°, Z = 2) the vanadium atoms which are bridged by the phenolate ligands show a square-pyramidal coordination sphere. The central atom in 2 (monoclinic, P2₁/c, a = 17.755(2) Å, b = 11.629(1) Å, c = 20.956(3) Å, β = 113.98(1)°, Z = 4) has a bipyramidal environment which is realized by coordination of a THF donor molecule. The (THF)₂Li fragment is bound via bridging phenolate ligands. The structure of 3 (orthorhombic, P2₁2₁2₁, a = 15.465(2) Å, b = 15.456(2) Å, c = 15.469(2) Å, Z = 4) is built up by two tetrahedrons linked by the oxo atom. Dimeric 6 (triclinic, P1, a = 10.780(4) Å, b = 11.428(2) Å, c = 13.734(3) Å, α = 77.24(2)°, β = 84.79(2)°, γ = 74.35(2)°, Z = 1) has a structure similar to 1 . The vanadium atoms are bridged by two OH groups while phenolate ligands link the lithium cations with the vanadium atoms.