Bis(arene)vanadium(O) complexes as a source of vanadium(II) derivatives by both disproportionation of the [V(η 6-arene) 2] + cations and oxidation. of [V(η 6-arene) 2

Abstract

The [V(η 6-arene) 2] + cation (arene = benzene, toluene or mesitylene) is disproportionate to [V(η 6-arene) 2] and V II compounds in ether solvents such as THF or 1,2-dimethoxyethane (DME). The extent of disproportionation depends on the nature of both the counteranion and the arene ligand. Addition of the filtered crude reaction mixtures, presumably containing the [V(η 6-arene) 2][Al 2X 7] derivatives, to THF gave [V 2(μ-X) 3(THF) 6[AlX 4] (arene = benzene or toluene; X = Cl or Br). For X = Cl and arene = toluene, addition to a THF solution of LiI yielded [V 2(μ-Cl) 3(THF) 6]I. The atom connectivity was established for [V 2(μ-Cl) 3(THF) 6][AlC 4], while [V 2(μ-Cl) 3(THF) 6]I was fully characterized by X-ray diffraction methods. Crystal data: [V 2(μ-Cl) 3(THF) 6]I: monoclinic, space group C2/ c (no. 15), a 25.199(8), b 13.865(6), c 9.879(4) Å, β 103.98(2)°, V 3349.3 Å 3, Z = 4, D c 1.523 g cm ]t-3, μ 17.256 cm −1, F(000) = 1560. The vanadium(II) derivative VI 2(THF) 0.7 was obtained, together with [V(η 6-mesitylene) 2] in the reaction of [V(η 6-mesitylene) 2][AlI 4] with THF. By reaction of [V(η 6-mesitylene) 2] with CPh 3X (X = Br or I) in 1,2-dimethoxyethane (DME), the dihalides of vanadium(II), [VX 2(DME) 2] have been isolated in good yields. The crystal and molecular structure of the monomeric cis-[VI 2(DME) 2] of pseudo-octahedral geometry has been studied by X-ray diffraction methods. Crystal data: [VI 2(DME) 2]: monoclinic, space group P2 1/ n (non-standard No. 14), a 7.819(4), b 13.150(4), c 15.535(5) Å, β 90.23(3)°, V 1597.3(1) Å 3, Z = 4, D c 2.017 g cm −3, μ 44.231 cm −1, F(000) = 916.