ISSN:
0947-6539
Keywords:
homogeneous catalysis
;
metallocenes
;
polymerization
;
Ziegler catalysts
;
zirconium complexes
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
(Butadiene)zirconocene adds to B(C6F5)3 to form the metallacyclic metallocene-boron betaine system 1, which contains a C-F → Zr interaction. Addition of tert-butylisocyanide or tert-butyl-cyanide leads to cleavage 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 η2-imino-acyl betaines 5 and 6 (2 stereoisomers), whereas 7 inserts additional tert-butyl-cyanide into the Zr-C bond to give a chiral metallacyclic N-zirconaketimine complex that is probably stabilized by an internal borate → 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°C in [D8]toluene solution, are chiral and are also stabilized by internal borate → Zr coordination. Complexes 9 and 10 are likely to be intermediates in the formation of active homogeneous Ziegler polymerization catalysts.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chem.1460020803
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