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 { η5‐(C5H4)B(NiPr2)NHtBu} 2 {N(SiMe3)2} ] (2) and [Zr {η5‐(C9H6)B(N(SiMe3)2)(C9H7)} Cl2] (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 © 2003 John Wiley & Sons, Ltd.