Syntheses and structural characterization of 2,2'-methylene-bis (6-t-butyl-4-methyl-phenoxide) complexes of titanium, zirconium and tantalum

The reactions of M(NMe2)(n) (M = Ti, Zr, n = 4; Ta, n = 5) with 2,2'-methylene-bis (6-t-butyl-4-methylphenol), HO-CH2-OH, in toluene produce Ti(O-CH2-O)(2) (1), Zr-2(eta(2)-O-CH2-O)(2)(mu,eta(1)-O-CH2-O)(2) (2) and Ta(O-CH2-O)(NMe2)(3) (3). Compounds 1 and 2 can also be obtained oia metathesis of MCl4 with Li-2(O-CH2-O). Reducing (O-CH2-O)TiCl2 with 2 equiv. of Na/Hg also generates 1 by ligand redistribution. Reaction of Zr(NM2)(4) with 1 equiv. of HO-CH2-OH yields (O-CH2-O)Zr(NMe2)(2) (4). Metathesis of TaCl5 with 1 equiv. of Li-2(O-CH2-O) produces (O-CH2-O)TaCl3 (5). (O-CH2 -O)Ta(NMe2)(2)Cl (6) is formed from the reaction of 3 with 1 equiv. of trimethylsilylchloride in toluene. The dimethylamide groups of compounds 3 and 4 reveal dynamic behavior on the NMR time-scale. The compounds 1, 2 and 3 have been characterized by single-crystal X-ray crystallography. (C) 1997 Elsevier Science Ltd.