Synthesis and structure of [1,2-bis(1-indenyl)benzene]titanium and zirconium dichlorides

Abstract

The palladium-catalyzed coupling of 1,2-diiodobenzene with indenylzinc complexes obtained from indene, 4-methylindene, 4,7-dimethylindene and hydrindancene gave 1,2-bis(1-indenyl)benzenes in 29–45% yield. New phenyl-bridged ansa-bis(indenyl)titanium and -zirconium dichlorides were obtained from these ligands in good yield either by addition of TiCl 3 or ZrCl 4 to their lithium salts (61–92% yield) or by addition of Zr(NMe 2) 4 to the neutral ligands (59–67%). In each case the zirconium tetraamide metalation gave very high dl-selectivity. The n-BuLi/ZrCl 4 metalation of the phenyl-bridged unsubstituted indene gave a 3:2 ratio of dl- to meso- while placing substituents at the 4,7- and 5,6-positions led to 10:1 selectivity in favor of the dl-isomer. The n-BuLi/TiCl 3 metalation gave between 1:1 and 4:1 selectivity. The solid state structure of [1,2-bis(1-indenyl)benzene]dichlorozirconium ( dl- 6a) was obtained by X-ray analysis.