Synthesis and structure of [1]borametallocenophanes of titanium, zirconium, and hafnium

Various [1]borametallocenophane complexes of all the group IV metals were o btained in high yield by a very efficient multistep, one-pot synthesis. By this method not only the biscyclopentadienyl and diindenyl complexes [{R2NB (eta(5)-C5H4)(2)}MCl2] (M = Zr, R = Me, SiMe3, 4a, b; M = Hf, R = SiMe3, 5) and [{(Me3Si2)NB(eta(5)-C9H6)(2)}MCl2] (M = Ti, 6; M = Zr, 7) were obtaine d, but also complexes with two different eta(5)-coordinated ligands such as [{iPr(2)NB(eta(5)-C5H4) (eta(5)-C9H6)}MCl2] (M = Zr, 8; M = Hf, 9) Some of compounds 4-9 were chosen to investigate their catalytic properties with r espect to Ziegler-Natta-type polymerisation of olefins, and proved to be hi ghly efficient for the preparation of polyethylene.