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)(2)OVCl2(mu -OMes)](2) (1) which can be converted with excess LiOMes to the substitutio n product [Li(THF)(2)OV(OMes)(3)(THF)] (2). Treatment of (1) with LiMes res ults in the formation of complexes [Li(THF)(3)OVMes(3)] (3) and [Li(THF)(3) OvMes(2)(OMes)] (4). Complex [(Li(THF)(2)Ov(OMes)(2)(mu-OH))(2). 2THF] (6) has been isolated as a by-product of an unknown reaction of [OV(OMes)(3)] a nd Li. The structures of 1, 2, 3, and 6 have been determined by X-ray analy sis. In 1 (monoclinic, P2(1)/c, a = 9.522(1) Angstrom, b = 19.777(2) Angstr om, c = 12.311(1) Angstrom, beta = 104.45(1)degrees, Z = 2) the vanadium at oms which are bridged by the phenolate ligands show a square-pyramidal coor dination sphere. The central atom in 2 (monoclinic, P2(1)/c, a = 17.755(2) Angstrom, b = 11.629(1) Angstrom, c = 20.956(3) Angstrom, beta = 113.98(1)d egrees, Z = 4) has a bipyramidal environment which is realized by coordinat ion of a THF donor molecule. The (THF)(2)Li fragment is bound via bridging phenolate ligands. The structure of 3 (orthorhombic, P2(1)2(1)2(1), a = 15. 465(2) Angstrom, b = 15.456(2) Angstrom, c = 15.469(2) Angstrom, Z = 4) is built up by two tetrahedrons linked by the oxo atom. Dimeric 6 (triclinic, <P(1)over bar >, a = 10.780(4) Angstrom, b = 11.428(2) Angstrom, c = 13.734 (3) Angstrom, alpha = 77.24(2)degrees, beta = 84.79(2)degrees, gamma = 74.3 5(2)degrees, Z = 1) has a structure similar to 1. The vanadium atoms are br idged by two OH groups while phenolate ligands link the lithium cations wit h the vanadium atoms.