TITANIUM AND ZIRCONIUM COMPLEXES CONTAINING A NOVEL DIANIONIC TRIFUNCTIONAL AMIDO LIGAND

The novel tridentate diamidoamine Ligands [RC(2-C5H4N)(CH2NSiMe3)(2)]( 2-) (R = H, CH3) have been synthesized and coordinated to Ti-IV and Zr -IV giving the pentacoordinate complexes [MX2{RC(2-C5H4N)(CH2NSiMe3)(2 )}] (M = Ti, Zr; X = Cl, Br). The crystal structure analysis of [TiBr2 {HC(2-C5H4N)(CH2NSiMe3)}] (10b) confirmed the involvement of the pyrid yl function in the coordination to the metal centre occupying an apica l position in the trigonal bipyramidal Ligand polyhedron. Alkylation o f [TiCl2{H3CC(2-C5H4N)(CH2NSiMe3)(2)}] (12a) with one or two molar equ ivalents of [RMgCl] (R = PhCH2, Me3SiCH2, Me3SiC2) yielded the mono- a nd dialkyl complexes [TiClR{H3CC(2-C5H4N)(CH2NSiMe3)(2)}] and [TiR2{H3 CC(2-C5H4N)(CH2NSiMe3)(2)}] in good yields. Depending on the steric de mand of the alkyl group coordination or decoordination of the pyridyl group leads to four-or five-coordinate species. A crystal structure an alysis of the pentacoordinate complex [TiCl(CH2SiMe3){H3CC(2-C5H4N)(CH 2NSiMe3)(2)}] (16) was carried out.