SYNTHESIS OF PERMETHYLINDENYL COMPLEXES OF THE EARLY TRANSITION-METALS - CRYSTAL-STRUCTURES OF TI(ETA(5)-C(9)ME(7))CL-3 AND ZR(ETA(5)-C(9)ME(7))(2)CL-2

Addition of 1-(trimethylsilyl)heptamethylindene (C(9)Me(7)SiMe(3)) to a suspension of the anhydrous halides MCl(4) (M = Ti, Zr, and Hf) in T HF gives the half-sandwich complexes M(eta(5)-C(9)Me(7))Cl-3 (M = Ti, Zr, and Hf) in good yield. Ti(eta(5)-C(9)Me(7))(2)Cl-3 crystallizes in the centrosymmetric orthorhombic space group Pbca with a 16.875(4) An gstrom, b = 14.706(3) Angstrom, c = 13.781(3) Angstrom, V = 3420 Angst rom(3), Z = 8, R = 0.047, and R(W) = 0.049. The Ti-C distances range f rom 2.352(4) to 2.400(4) Angstrom with a mean value of 2.370(5) Angstr om and are consistent with symmetrical bonding of the indenyl ligand t o the metal center. The Ti-(eta(5)-ring centroid) distance is 2.036(4) Angstrom. Addition of 2 equiv of lithium heptamethylindenide (Li(+)C( 9)Me(7)(-)) to the anhydrous halides MCl(4) (M = Zr and Hf) in THF giv es the metallocene derivatives M(eta(5)-C(9)Me(7))(2)Cl-2 (M = Zr and Hf) in good yield. Zr(eta(5)-C(9)Me(7))(2)Cl-2 crystallizes in the cen trosymmetric monoclinic space group P2(1)/n with a = 14.951(12) Angstr om, b = 13.523(6) Angstrom, c = 13.913(11) Angstrom, beta = 96.46(3)de grees, V = 2795.5 Angstrom(3), R = 0.041, and R, = 0.048. The Zr-C dis tances range from 2.511(4) to 2.612(4) Angstrom, with a mean value of 2.563(4) Angstrom, and are consistent with symmetrical eta(5)-bonding of both indenyl ligands to the metal center. The Zr-(eta(5)-ring centr oid) distances are 2.259(4) and 2.255(4) Angstrom with a centroid-Zr-c entroid angle of 139.0(4)degrees. The indenyl ligands are oriented awa y from the chloride ligands which causes a significant distortion from planarity by folding at the bridgehead carbon atoms.