REACTION COURSES FOR FORMATION OF EARLY TRANSITION-METAL PHENOXIDES

The 1:1 and 1:2 reactions of TiCl4 with Me3SiO-2,6-(CH3)2C6H3 produced TiCl3[O-2,6-(CH3)2C6H3]2(THF)2 (1) and TiCL2[O-2,6-(CH3)2C6H3]2(THF)2 (2), respectively, bearing six-coordinated geometry around Ti. The co mpound 2 assumes the cis-geometry regarding the two phenoxy groups and THF is coordinated in the trans position of the phenoxy groups. Simil arly, the 1:1 and 1:2 reactions of NbCl5 with the trimethylsilyl pheny l ether provided NbCl4[O-2,6-(CH3)2C6H3]2(THF) (7) and NbCl3[O-2,6(CH3 )2C6H3]2(THF) (8), respectively, with octahedron structure. The THF mo lecule 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. Tung sten mono-phenoxide, WCl5[O-2,6(CH3)2C6H3]2 (12), also has octahedron structure. In cases of tungsten-bis-phenoxides, WCl4[O-2,6-(CH3)2C6H3] 2 (13) and WCl4[O-2,6-(i-C3H7)C6H3]2 (14), the former has trans struct ure while the latter has cis structure regarding the phenoxy groups. A unique square pyramidal geometry has been observed in the tetrakis(ph enoxy) tungsten, WCl[O-2,6-(CH3)2C6H3]4 (16).