Zirconium Chelates of a Bulky Ferrocene-Based Diamido Ligand

The arylamino-substituted ferrocene derivative {Fe[C 5 H 4 (NH-2,4,6- i Pr 3 -C 6 H 2 )] 2 } ( 1b ) reacts with Zr(CH 2 Ph) 4 and Zr(NMe 2 ) 4 to afford the respective zirconium chelates [(PhCH 2 ) 2 Zr{Fe[C 5 H 4 (N-2,4,6- i Pr 3 -C 6 H 2 )] 2 }] ( 2 ) and [(Me 2 N) 2 Zr{Fe[C 5 H 4 (N- i Pr 3 -2,4,6-C 6 H 2 )] 2 }] ( 3 ), which exhibit unexpectedly low catalytic activity in the polymerization of ethylene after activation with MAO and [Ph 3 C][B(C 6 F 5 ) 4 ], respectively. In order to elucidate stereoelectronic effects of the bulky aryl substituents, the structures of 2 and 3 and of their parent ferrocene derivative 1b have been determined as well as that of the phenylamino analogue {Fe[C 5 H 4 (NHPh)] 2 } ( 1a ), for which an improved synthesis has been developed.