Reaction courses for formation of early transition metal phenoxides

Article abstract of DOI:10.1016/0022-328X(94)80111-8

The 1 : 1 and 1 : 2 reactions of TiCl4 with Me3SiO-2,6-(CH3)2C6H3 produced TiCl32(THF)2 (1) and TiCl22(THF)2 (2), respectively, bearing six-coordinated geometry around Ti.The compound 2 assumes the cis-geometry regarding the two phenoxy groups and THF is coordinated in the trans position of the phenoxy groups.Similarly, the 1 : 1 and 1 : 2 reactions of NbCl5 with the trimethylsilylphenyl ether provided NbCl42(THF) (7) and NbCl32(THF) (8), respectively, with octahedron structure.The THF molecule again locates in the trans position of a phenoxy group in both cases and the two phenoxy groups of 8 locate in the cis position.Tungsten mono-phenoxide, WCl52 (12), also has octahedron structure.In cases of tungsten bis-phenoxides, WCl42 (13) and WCl42 (14), the former has trans structure while the latter has cis structure regarding the phenoxy groups.A unique square pyramidal geometry has been observed in the tetrakis(phenoxy) tungsten, WCl4 (16).Key words: Titanium; Niobium; Tungsten; Zirconium; Tantalum