OBSERVING A HOMOGENEOUS ZIEGLER CATALYST PRECURSOR AT WORK - INSERTION REACTIONS INTO THE ZIRCONIUM-CARBON BOND OF THE (BUTADIENE)ZRCP(2) B(C6F5)3 ADDITION PRODUCT/

(Butadiene)zirconocene adds to B(C6F5)(3) to form the metallacyclic me tallocene-boron betaine system 1, which contains a C-F --> Zr interact ion. Addition of tert-butylisocyanide or tert-butylcyanide leads to cl eavage of the zirconium-fluorine linkage and formation of the adducts 4 and 7, respectively. With additional tert-butylisocyanide, 4 reacts further to yield the corresponding eta(2)-iminoacyl betaines 5 and 6 ( 2 stereoisomers), whereas 7 inserts additional tert-butylcyanide into the Zr-C bond to give a chiral metallacyclic N-zirconaketimine complex that is probably stabilized by an internal berate --> Zr interaction. Ethene and propene insertion reactions into the Zr-C bond of 1 follow a similar course: the mono-insertion products 9 and 10, respectively, generated in situ and characterized by NMR spectroscopy at -35 degree s C in [D-8]toluene solution, are chiral and are also stabilized by in ternal berate --> Zr coordination. Complexes 9 and 10 are likely to be intermediates in the formation of active homogeneous Ziegler polymeri zation catalysts.