Synthesis and structures of [Yb{η5-(C5H4)B(NiPr2)NHtBu}2{N(SiMe3)2}] and [Zr{η5-(C9H6)B(N(SiMe3)2)(C9H7)}Cl2]

Both amido-(cyclopentadienyl)boranes and bis(cyclopentadienyl)boranes of the types R2NB(CxHy) (NR') and R2NB(CxHy)(2) (R = alkyl, trimethylsilyl; R' = Ph; CxHy = C5H5 (cyclopentadienyl), C9H7 (indenyl), C13H9 (fluorenyl)) were recently shown to form corresponding boron-bridged Group 4 metallocenes that exhibit high activities in Ziegler-Natta-type catalysed olefin polymerization. Here, the same boranes were utilized in the formation of metallocenes of ytterbium. and zirconium, where the ligands selectively bind in a non-chelate fashion. The resulting complexes [Yb(eta(5)- (C5H4)B((NPr2)-Pr-i)(NHBu)-Bu-t)(2) (N(SiMe3)(2))] (2) and [Zr(eta(5)-(C9H6)B(N(SiMe3)(2))(C9H7))Cl-2](4) allow studies on these ligands in a metal-bonded, though unstrained, environment. Furthermore, these complexes might find use as precursors in the formation of organometallic polymers, since they exhibit a readily available moiety for the coordination of further transition metal centres. Both complexes were fully characterized by multinuclear magnetic resonance spectroscopy and X-ray structure determination. Copyright (C) 2003 John Wiley Sons, Ltd.