o-(Cyclohexyliminoethyl)(arylamido)benzene and related complexes of zirconium and titanium. The non-innocence of the ketimino functionality

Abstract

N-Arylamido complexes of zirconium in which the amido functional group is attached to an o-(alkyliminoethyl) substituted aromatic ring, have been synthesised by salt elimination reactions and characterised by spectroscopic and diffraction methods; they are analogous to the N-silylamido species recently reported (Dalton Trans., 2002, 3290–3299). The ligands 2-[CyNC(CH₃)]C₆H₄N(H)(xyl), L^xylH, and 2-[CyNC(CH₃)]C₆H₄N(H)(mes) L^mesH, Cy = C₆H₁₁, xyl = 3,5-Me₂C₆H₃ mes = 2,4,6-Me₃C₆H₂, were prepared in good yields by Buchwald–Hartwig amination of the arylbromides with 2-[CyNC(CH₃)]C₆H₄NH₂. Reaction of L^mesLi with Zr(NEt₂)₂Cl₂(thf)₂ gave after chloride substitution the arylamido ketimino complex L^mesZr(NEt₂)₂Cl 1; variable amounts of the arylamido vinylamido complex 2 were also obtained. Interaction of L^mesLi or L^xylLi with Ti(NMe₂)₂Cl₂ gave rise to the tripodal bis-amido amino complexes 5 and 6 possibly formed by ligand rearrangement involving migration of the dimethylamido group to the ketimino carbon.