Exposure of the isolable zirconocene sandwich compounds, (η5-C5Me5)(η5-C 9H5-1-R1-3-R2)Zr (R1 = Me, iPr, tBu; R2 = Me) to one atmosphere of dinitrogen resulted in N2 coordination. X-ray diffraction and NMR spectroscopy establish that the resulting dimeric dinitrogen compounds contain an unusual μ2,η2-bridging indenyl ring and a weakly activated N2 ligand. N2 coordination from the isolable zirconium sandwich compounds is extremely sensitive to the number and size of the indenyl subsituents. Compounds bearing two [iPr] or three methyl substituents are stable as η9 sandwich compounds for weeks under dinitrogen likely due to the inability to dimerize through a two-atom N 2 bridge. Performing the reduction of (η5-C 5Me5)(η5-C9H5-1- R1-3-R2)ZrCl2 (R1 = iPr, tBu; R2 = Me; R1 = R2 = SiMe 3) under an N2 atmosphere produced a different outcome; rare examples of side-on, end-on zirconium dinitrogen compounds were isolated and in one case, crystallographically characterized. Protonolysis studies with weak Brønsted acids were used to evaluate the relative activation of the bridging dinitrogen ligands.
|Original language||English (US)|
|Number of pages||8|
|Journal||Journal of the American Chemical Society|
|State||Published - May 7 2008|
All Science Journal Classification (ASJC) codes
- Colloid and Surface Chemistry