Reaction of the Lewis acids B(C6F5)(3) and (AlMe2Cl)(2) with azazirconacycles

B(C6F5)(3) opens the ring of the N-Bu-t azazirconacyclobutane 2 by abstract ing the carbon from the zirconium; the resulting amido cation 3 reacts slow ly with ethylene to form a chelating gamma-iminoalkyl zirconocene cation, 4 . Similarly, B(C6F5)(3) removes carbon from the Zr of the N-Ph azazirconacy clopentane 5a and the N-SiMe3 azazirconacyclopentane 5b, forming amido cati ons that are stabilized in the solid state by coordination of phenyl substi tuents on N (6, from 5a) or C (8, from 5b); 8 slowly loses hydrogen, formin g an azaallyl cation 9. In contrast AlMe2Cl coordinates the N of the zircon aaziridines 10, resulting in an sp(2) N coordinated to Zr through a p orbit al. The structures of 4, 6, 8, and 11a have been established by X-ray cryst allography.