831174-63-1Relevant academic research and scientific papers
Zirconium sandwich complexes with η9 indenyl ligands: Well-defined precursors for zirconocene-mediated coupling reactions
Bradley, Christopher A.,Keresztes, Ivan,Lobkovsky, Emil,Young, Victor G.,Chirik, Paul J.
, p. 16937 - 16950 (2004)
A family of isolable, well-defined bis-indenyl zirconium sandwich complexes, (η5-C9H5-1,3-R 2)-(η9-C9H5-1,3-R 2)Zr (R = silyl, alkyl), have been prepared by either alkane reductive elimination or alkali metal reduction of a suitable zirconium(IV) dihalide precursor. Crystallographic characterization of two of these derivatives, R = SiMe2CMe3 and CHMe2, reveals unprecedented η9 coordination of one of the indenyl ligands. Variable-temperature and EXSY NMR studies establish that the η5 and η9 rings are rapidly interconverting in solution. The sandwich complexes serve as effective sources of low-valent zirconium reacting rapidly with both olefins and alkynes at ambient temperature. In contrast to bis-cyclopentadienyl chemistry, the olefin adducts of the bis-indenyl zirconium sandwiches undergo preferential C-H activation to yield the corresponding allyl hydride compounds, although reaction with excess olefin proceeds through the η2-olefin adduct, forming the corresponding zirconacyclopentane.
