| abstract |
Metallocenes of formula (I) are new: M = Ti, Zr, Hf, V, Nb, Ta or a lanthanide; X1, X2 = 1-10C alkyl or alkoxy, 6-10C aryl or aryloxy, 2-10C alkenyl, 7-20C arallyl or alkaryl, 8-20C aralkenyl, H or halo; L1, L2 = (a) opt. mono- or poly-substd. mono- or poly-nuclear hydrocarbon residue with at least one cyclopentadienyl (Cp) unit, which can form a sandwich structure with M, where L1 and/or L2 is substd. and/or condensed with one or more ferrocene (Fc) or ruthenocene (Rc) gps. which are opt. substd. with X1/X2 or a Fc or Rc gp.; or (b) L1 = opt. mono- or poly-substd. Cp-contg. residue, opt. substd. and/or condensed with opt. substd. Fc or Rc as in (a), and L2 = amido, phosphido or arsenide gp. of formula E-D less than (with D = N, P or As; E = as for X+1, X2) R1 = C, Si, Ge or Sn, or the whole gp. A(R1)nB = biphenylene gp., opt. substd. with A and/or B; A, B = as for X1 and X2; n = 0.4; if n = 0, the free valencies on L1 and L2 substd. with X1 or X2, with the condition that n is not zero if L2 = amido, phosphido or arsenide gp. Also claimed the prodn. of (I) by reacting a cpd. of formula (II) with a cpd. of formula (III) (see above; with M' = alkali metal; X' = halo). Also claimed is the prodn. of polyolefins by polymerisation of olefins using (I) as catalysts, pref. with aluminoxanes as cocatalysts. |