Reaction of the Lewis Acids B(C6F5)3 and (AlMe2Cl)2 with Azazirconacycles
journal contributionposted on 18.08.1999, 00:00 by C. Jeff Harlan, Brian M. Bridgewater, Tony Hascall, Jack R. Norton
B(C6F5)3 opens the ring of the N-tBu azazirconacyclobutane 2 by abstracting the carbon from the zirconium; the resulting amido cation 3 reacts slowly with ethylene to form a chelating γ-iminoalkyl zirconocene cation, 4. Similarly, B(C6F5)3 removes carbon from the Zr of the N-Ph azazirconacyclopentane 5a and the N-SiMe3 azazirconacyclopentane 5b, forming amido cations that are stabilized in the solid state by coordination of phenyl substituents on N (6, from 5a) or C (8, from 5b); 8 slowly loses hydrogen, forming an azaallyl cation 9. In contrast AlMe2Cl coordinates the N of the zirconaaziridines 10, resulting in an sp2 N coordinated to Zr through a p orbital. The structures of 4, 6, 8, and 11a have been established by X-ray crystallography.