Synthesis, structures and catalytic properties of chelating N,N '-bis(silylated) 1,2-benzenediamidozirconium(IV) chlorides [and a titanium(IV) analogue] and dimethylamides

Chelating diamido ligands of formula [C6H4{N(SiMe2X)}(2)-1,2](2-), abbrevia ted as L'(2-) (X=CH=CH2) or L2- (X=Me), were used to prepare di(amido)metal (IV) chlorides [{M(Cl)L'(mu -Cl)(thf)}(2)] (M=Zr 2 or Ti 3), ZrCl2(L') 5 an d [ZrCl2(L)(tmen)] 6 and the heteroleptic amides [{Zr(NMe2)(L-x)(mu -NMe2)} (2)] (L-x=L' 4 or L 7). Complexes 2 and 3 were obtained from equivalent pro portions of Li2L' (prepared in situ from H2L' 1) and the appropriate metal chloride [MCl4(thf)(2)], while [Li-2(L)(tmen)(2)] and ZrCl4 furnished 6. Tr eatment of Zr(NMe2)(4) with an equivalent portion of H2L' or H2L gave 4 and 7, respectively. Complex 5 was obtained from 4 and Si(Cl)Me-3, and with th f yielded 2. The crystal structures of 2, 4, 6 and 7 have been determined. Compounds 2 and 4-6, unlike the less active titanium complex 3, were active catalysts with methylaluminoxane (AlMeO)(n) for polymerisation of ethene a nd the resulting polymers were shown to have extremely high average molecul ar weights, as determined by viscosity measurements.