Synthesis and X-ray crystal structures of rac-and meso-2,2′-propylidene-bis( 1-indenyl) zirconium dichlorides

An improved synthesis of 2,2′-bis(1-indenyl)propane and the corresponding ansa-complexes of zirconium are reported. Synthesis of a mixture of rac - and meso -2,2′-propylidene-bis(1-indenyl)zirconium dichlorides involves a treatment of ZrCl 4 with bis[3-(trialkyltin)inden-1-yl]propane, where alkyl = ethyl, butyl, in toluene. This reaction gives the products in 92% yield and might be a convenient synthetic pathway to a number of straightforward ansa -metallocenes. Both rac - and meso -2,2′-propylidene-bis(1-indenyl)zirconium dichlorides were separated and isolated using simple work-up processes, and characterized by X-ray crystal structure analysis ( rac : C 2/ c ; a = 15.903(3) Å, b = 11.105(2) Å and c = 11.520(2) Å; β = 121.61(3)°; Z = 4; V = 1732.6(5) Å 3 ; R = 0.0350; meso -: P 1¯; a = 9.739(2) Å, b = 12.798(4) Å and c = 15.322(4) Å; α = 101.18(2)°; β = 121.61(2)°; γ = 90.54(2)°, Z = 4; V = 1795.4(8) Å 3 ; R = 0.0417).